Adequan Reaction?

My 4 year old cat has urinary tract issues and has been receiving Adequate shots every 6 to 8 weeks for, approximately, the last two years. In the past he has never has a reaction to the medication. This time, however, the doctor mentioned that he "might be sore". Well, he is sore, to the point that he doesn't like to be touched and, in my opinion, is pretty much acting like he is very, very ill (sleeping in odd places and positions, not speaking, breathing too fast). Has anyone experienced this before?

I don't have any experience with this but it definitely sounds like I'd put a call in to the vet, especially since he's never reacted like this to this same medication.

The vet may have injected the wrong place or the wrong way, into the muscle instead of under the skin, etc. It seems odd he would 'warn' you like that, SOMETHING happened . I would call him, describe what your cat is doing and ask what he meant by what he said.  Your description sounds like pain to me. Maybe he can give you some pain medicine.