cat sinus congestion

We have a 13 year old male cat who has some kind of sinus infection. He has been treated 3x with prescriptions and has had 2 X-ray's. The Vet is baffeled, as nothing shows in the X-ray. It is going on 3 months. He eats and functions fine, but the clogged head and mucus is not going away and he must be suffering to some extent.
Any suggestions!

We have a 13 year old male cat who has some kind of sinus infection. He has been treated 3x with prescriptions and has had 2 X-ray's. The Vet is baffeled, as nothing shows in the X-ray. It is going on 3 months. He eats and functions fine, but the clogged head and mucus is not going away and he must be suffering to some extent.
Any suggestions!

Time for your vet to run a culture & sensitivity...this takes time, 24 hours for the culture (to see what grows)..and 24 hours for the sensitivity.( to see what antibiotic is sensitive to what grows) Organisms can be resistant as can bacteria...using any antibiotic can be a waste of money and/or stripping your pet of vital immunity when the antibiotic could actually work...sometimes an antibiotic has to be "fitted" to fight the cause. The sensitivity test will show a panel of what works the best down to what had the least response.
Good luck and Thank you for going the mile for your kitty!
Keep us posted!