cat sneezing alot. no nasal drip. is it still URI?

Hello,

Last week my cat had congestion, watery eyes and a coughing/hacking episode (no respiratory distress). I took her to the vet and she suspected asthma and gave my cat a depo-medrol shot. 2 days on the cat still had the same symptoms+coughing episode. I took her to another vet who suspected URI and prescribed Clavamox 1.2ml 2/day. On day 4 of the clavamox she developed sneezing bouts (sneezing was not present before). I took her to the vet again and they told me to give her clavamox for another week.  We are on day 7 of the clavamox with the sneezing bouts remaining and a little watery eyes. There is no nasal discharge. The sneezed up stuff is clear and thin (not mucous-y). I am not feeling very confident with the antibiotic right now. Should I just wait for a few more days and see how it progresses? Does anyone have any experience with this? Or can someone please suggest how I can make her more comfortable when sneezing?

I have changed the litter type and am trying the 15-20 minute sessions in a steamed bathroom.

Are there any supplements I can give her to support her immune response (wild salmon oil perhaps?)

It could be, but it could also be seasonal allergies or even allergy to the litter.  You can use saline drops such as Little Noses in the nostril to help with the congestion and clear the nose.  As for overall health, trying L-Lsyine might help, but it takes up to a month to see any benefits.