Please help me!

Question
They don't have any problem with hairloss and Peaches still eats like a...well...piggie :)  But Cream never has eaten a tremendous amount, so it really concerns me when she seems to look smaller than usual.  And the head thing is really annoying to her.  I dunno if it helps, but Peaches had just gotten over a UTI. The vet had prescribed Baytril (1 CC/7 days) because she had been having a signifigant amount of blood in her urine and was crying & lifiting her rear when she went to the bathroom. An X-ray showed nothing abnormal, and once the treatment started, she was fine.  The crying and straining and blood disappeared.  Cream had shown no signs of having a UTI, so she wasn't treated.  However, once the treatment started, Peaches had horrible diarrhea.  I figure it killed the good & bad bacteria in her intestines.  So, I got some "DriTail" and gave them that (after Peaches had finished her medication).  I also had called my vet back and they didn't know what to do other than give her plain yogurt - the kind w/the live bacteria cultures in it.  They said it would re-establish the good bacteria.  I dunno about that. It didn't seem to help and they didn't like to eat it.  I even tried flavored yogurt but they still won't eat it.  I found bananna flavored "Yogurt Dips" and Cream loves those.  But the diarrhea still appears. It's not so horrible when they get the DriTail religiously, but if I stop, or haven't given it to them first thing in their water in the morning, they have diarrhea by mid-afternoon - really bad.  I dunno if this is linked to it...it probably is...but it does seem to go away for awhile, then it reappears with a vengence.  Poor Cream is half distraught because she can't even relax properly without her head twitching - which, although kinda funny but sad, it poses a real problem for her because she insists on laying under the nearest water bottle and she sometimes hits her head (not really hard, but still) on it.  I don't know. Maybe this will help narrow things down a bit.  I really appreciate your time and assistance with this problem.
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Followup To
Question -
I own 2 cavys, named "Peaches" and "Cream," who are about 4-5 years old.  They just got over a bad bout of diarrhea (Peaches decided to be nice and share with Cream). Anytime Cream goes to rest and lay down, her head twitches.  It really annoys her and concerns me.  I don't have any cavy vets close to me, and I've already "wasted" $200+ at my local vet only to find out that they have no clue what to do for her (they don't know much about cavys).  Nothing else seems to be wrong, except she's lost a little weight...of course, with Cream, that's bad because she's so tiny to begin with.  She was the runt of the litter and has remained smaller than her sister, Peaches, who's a sturdy butterball.  I'm afraid it could be serious, but I'm also hopeful it's only something minor.  Any ideas would be helpful...anything...I'm desperate for help.  Thanks so much for your time.
Answer -
sounds like it could be pneumonia starting, but no certainty of it. are they eatting and drinking normally? do they have some hair loss? if they are not eatting and have hairloss it could be mange which is a very serious problem. i don't know for sure what it is and i am sorry i can't help you much.
http://www.apapets.com/ this link can help you find the closest vet or humane society or vet emergancy hospital to you that cares for cavies and they can help. i hope i was of some assistance. if you need anymore help or have any more questions, please feel free to ask.

Answer
I'm sorry, I don't know what it could be other then maybe an infection of some sort. Don't give them yogurt, its not particuarly good for them. All I can say is try to find a vet for them, even if it may be a little bit of a drive. I'm sorry I can not be much of a help to you. Good luck.