I'm using flomist. can i scuba dive using nitrox?

Flomist is not sold: In the us. If it is fluticasone nasal spray for nasal allergy sxs - that suggests you may have nasal congestion which might impede your ability to clear your ears. If you have fluticasone systemic med for treatment of asthma that can be a serious problem when diving. Encourage you to see an undersea medicine physician to go over your health issues ; to determine if you are safe to dive.

Yes: I assume you're using it to prevent or treat symptoms of allergic rhinitis. Assuming that your symptoms at the time of diving are well controlled and you have no nasal or sinus congestion, I see no problem diving with any kind of breathing gas.