Oh dear I'm sorry he seems poorly again.
Things to consider:
Pain relief, is it enough?
Has he got ulcers in his mouth or fungal in his mouth that makes eating difficult/painful
Keeping his gut moving, syringe feeding mushed up pellets etc or CC.
Fluid intake-is he drinking enough if not he needs syringing water
You could try some pearl barley mash to offer him :
http://www.oginet.com/pgurney/cystitis.htm
Most piggies love it, it can do no harm.
Try him with a little fresh grass as long as he doesn't have a runny tummy.
Softening Wagg Optimum pellets, my piggies absolutely love these, they are small enough to soak slightly & offer him on a spoon or syringe feed them.
Check poop/pee output, if he doing enough of both?
Has he got a wet chin/or is he dribbling?
That probiotic is fine. From reading previous posts it sounds like Baytril is fairly hard on their tummies & can cause loss of appetite.
Fingers crossed for you both, hope he gets better very soon!