As they both have the same symptoms it is possible that it is something in the diet.Beetroot can cause stained urine.On the other hand it may be an infection.,.,you are doing nthe right thing in getting a vet to check them and do a urine test.
The easiest way to get a urine sample is to put the pig in a clean container such as a bowl,give it water by syringe and try and get it to eat diuretic foods such as dandelion,celery or parsly.Get a clean container ready.Suitable containers are tablet bottles or med bottles,very well washed out,or any small,glass bottle.You only need a small amount of urine,just enough for the vet to put a labstix in.Also have ready a 1ml or 2 ml syringe.As soon as the pig pees syringe it up and transfer to the container.If you have no suitable container you could leave it in the syringe.As you have 2 gps ,remember to put a name on each container.
Could I just say that sawdust is not a suitable bedding for gps as it can cause eye and respitory infections.It is just possible that the sawdust has caused this infection because it can get into the genital cavities and possibly fester.