Hi there. UTI is not uncommon and you are the second poster I've seen recently who has been prescribed Baytril once a day rather than the more traditional twice a day... but then again (depending on piggy's weight) you could regard that dose as a 'double'. You might ask when you go back why it was just once a day (it could be for a very sensible reason, maybe even a new veterinary protocol, but it's worth an ask to make sure it wasn't a mistake). Similarly with the metacam - it's a good dose especially if it is the 1.5mg/ml version - but as pigs have a fast metabolism it's usually given twice a day (even if the dose is therefore split ie: 0.3ml morning and evening).
Fist of all I'm really sorry for your situation - it's not easy to see them like this. Has there been any improvement at all in his symptoms since the antibiotic (AB) was started? Or has there been no real change.
As it says above you should see improvement in his symptoms within the first 1-3 days if an antibiotic is going to work (although always finish the course unless you are told not to). We've had a few cases where old faithful Baytril just hasn't worked (not that surprising, it's been around for yonks) and we've used another antibiotic - Septrin (also twice a day). When we've had this our course has been longer - typically about 3 weeks - but we've still seen the symptoms improve within the first few days, so they stop crying when peeing and if they have had wet, drippy bits this has dried up. Personally if I see no improvement after 3 days I usually contact my vet again at that point (and sometimes they put up an alternative AB for me to just go in and collect). 'Give it a week' is fine if you are talking about completing a course that works but if an AB is going to work it should start killing those bacteria straight away!
The x-ray is to look for sludge or stones. Sludge they can pass but it can be unpleasant. Stones - well we'll tackle that if we need to but boys do usually need surgery to remove them. Persistent UTI can trigger a stone so it's good that you're tackling this promptly. Take a look at their diet and try to reduce any unnecessary calcium if you can by limiting the pellets they eat, increasing their access to low Ca water (maybe using a filter or buying low Ca bottled water if necessary - it will depend where you are in the UK and how scummy your kettle gets as to how much of a problem this can be). Maybe add an extra water bottle or bowl. Keep them off brassicas for now as they also have quite high calcium - esp all the tasty stuff they love like curly kale etc. Lettuce, cucumber, bell pepper just for now until you can get this sorted. You can't 'cure' a stone this way but you can help make sure a straightforward UTI doesn't get unnecessarily complicated. My old boy had a stone removal this past month. He's 6 and it was a big deal for him but he's OK at the minute. We had some grunting when finishing a pee which started about a week after his surgery which I hadn't heard before but I think it might have been sludge (he has ongoing issues which might just be down to knackered old kidneys). I use a little AB syringe (the 1ml with a rubber stopper) to offer him a drink of water - the idea being that a full bladder dilutes out that plug of sludge and makes it easier to pass. Bigger syringes have no rubber bit and can jet water into piggy's mouth which is really risky as they can inhale it. These little 1ml jobs just dribble it in. The weird thing is that old George seemed to have a raging thirst - especially in the evenings which is when they get their pellets. My two girls have no bladder issues currently (touch wood!) and just look bewildered when I offer the water syringe but Georgie has been cheerfully glugging it down. I reckon it's something to do with his bladder issues but it's a plus that he's keen to have a little flush out every night. You might try this if you have your low Ca water ('soft' water) and a syringe that doesn't taste of baytril - because that's very bitter. If he's holding in pees because it hurts to go from a UTI it will concentrate his urine and increase the risk of sludge - so the sludge might not be the primary problem if you see what I mean. Sometimes people get an x-ray and see a stone and conclude that's why piggy is crying when he pees - well, it surely won't help the situation, but I'd still treat for UTI anyway if I had a choice because they're not mutually exclusive - you can get both! George had both - and tbh at first the UTI gave him more serious symptoms. His stone was a more long-term issue but his initial UTI made him really unhappy.
If you decide to go in for the x-ray some vets might want to put piggy under with a whiff of gas. Any more serious GA than that and I'd be a bit worried as GA is a risk for little furry things. As them what they plan to do. But some vets don't GA if they can help it - mine will routinely swaddle piggy tightly in a towel to get their shots. If you do find sludge don't panic - it could just be a temporary issue because of difficulty with infection. But if your boy actually looks unwell and is miserable in himself, hiding away etc. my money's on UTI - because by last Christmas George had a honking great bladder stone (it had just got bigger and bigger over a few months) and squeaked in pain when he peed, but between times he was wandering about and begging veggies like normal. When he had his UTI he hid in a snuggle bag all the time and you could hear him crying all over the house when he went. So I think in your shoes I'd want to try an alternative antibiotic - and watch out for any changes in appetite if one is straight after the other. Fibreplex is good - I usually mix a squirt of about a cm into around 20ml CC rather than offer it direct. My pigs have never wanted to eat it neat!
Good luck at the vets little fellow x
piggie Dexter also began painful shrieking when going to toilet post op and began to make noises like an abrupt harsh cough. Unfortunately, he developed a hernia post op 
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