Could alcohol be triggering my sinus allergies?

Yes: Alcohol causes nasal congestion by a different mechanism than an allergic one. Perhaps that's a good thing; i've yet to meet someone truly allergic to alcohol. Unfortunately it means that allergy & alcohol ingestion work together to make your stuffy nose & sinuses even worse than ether one alone. You probably won't get much enjoyment from alcohol when sinus or nasal allergies are acting up.

Probably not: But alcohol itself can produce the same symptoms - stuffy, runny nose, from directly releasing histamine. In addition, alcohol increases the chance of chronic infection, which worsens all of your symptoms. If you are talking social drinking (1-2 drinks once or twice a week), it probably is not a factor. But heavier and more regular drinking is not good for your sinuses, or for you>.