Possible vet-caused sickness

Last Saturday, I took Toothless to the vet because his ears have been bothering him. I was told he has mites, and was given some medicine, which is working fast. However, all this week he's had a slightly runny nose and has been sneezing all the time. He wasn't like this before the vet visit, so I can't help but think that he picked something up while there. I'm not sure what to do.

I really don't want to have to take him back to the vet, for a few reasons. One, his first visit traumatized him enough. I really don't want to put him through that again, especially not after just a week. Two, I can't help but think this is their fault, and I really don't want him to pick something else up if we go to have this checked out. And three, I don't have the money for another vet visit. I'm already having to make payments on the first because of the medicine. I really can't afford to pay MORE because of amother visit or some more medicine.

So, I'd like some advice. Does anyone know what might be wrong with him? Any advice on how to help him feel better? Is there anything I can do to hold the vet responsible for getting him sick? Help??

He likely has a uri.  Can you trying calling the vet and seeing if they're concerned?  He may need antibiotics.  It is possible that picked it up at the vet, but also possible that the stress of the visit brought out something that was underlying.