That is a good sign that you can smell strong odors. Go ahead and finish with the antibiotics. If the nasal spray is a steroid, that's okay to use. But note that a recent study suggests that one powerful antibiotic, Amoxicillin, was "not likely" to be effective against sinusitis. But it is possible, and could keep the infection from spreading.
If the prescribed treatment doesn't work, I'd suggest this:
http://www.medhelp.org/user_journals/show/2322
The Flip-Turn Sinus Flush is mildly risky, because you have to bend over to do it, preferably in a shower, but you can also do it outside on soft ground, or you can kneel down and lean over a bathtub with the shower running.
If you tryi it, make sure you look straight up at the end of the flush, to drain the saline from the area where your olfactory nerves are.
Lastly, I use a jar of cinnamon to mark progress in smell recovery.
Good luck, friggy