I have sinus congestion - no drainage - but can barely keep my eyes open. What is causing this?

Slept almost 9 hours last night. Was in the ER 2 days ago with an allergy induced asthma attack (my first one). I'm at my desk and am dizzy (I know that is sinuses) - but I can hardly keep my eyes open and I feel like I'm in a fog. Help!??!?!