Possible Misdiagnosis

Question
I took my dog  (Chihuahua) last Thursday to the emergency room because he was not eating and it looked like he had an infection on his penis. The vet gave him antibiotics. The antibiotics seem to be working, but we took him today to his regular vet for a check-up and because we are still very concerned. He gained a pound, but he looks as if though his back legs are in pain. He can't climb up the stairs or sofa. The vet said he had a fungus and gave us a shampoo to wash him every four days. Does this seem like a right diagnosis? He still doesn't want to eat very much, but he is drinking water. The fact that he is not his lively self is worrying me.

Answer
I would have him tested for Lyme Disease as a fungal skin infection or penile infection should not affect his ability to walk.  If the Lyme test is negative, then he should have x-rays of his back and legs taken.  If he is not neutered, have the vet do a rectal exam to check his prostate.

Try offerring him meat baby food with boiled chicken and rice plus plain yogurt.