Ok. Nearly all sinus infections are caused by fungus, not bacteria. Antibiotics and steroids just pour gasoline on the fire. There are several ways to combat this, the best plans include a biofilm buster like edta and then its a good idea to follow up with probiotics. Just like clearing it out of the gut. You can use a nettie pot, nasal spray bottles, or a nebulizer for the antifungal application, then use a nettie pot to administer the probiotics.
Getting rid of the fungus and getting the gut functioning better should help with the asthma, maybe even alot. Quercitin and glutamine might be a good thing to try for you. Getting your vit d level up to 60+, even 70, is said to help asthma alot too.
Eat any of the carbs listed already