Can allergies cause dizziness, headaches, and nausea?!

I hae had allergies since I was a little. A couple of days ago, I woke up and saw the room spinning. I had to stand still to make that feeling go away. When I tried to go back to sleep, as soon as I laid my head down, the dizzy feeling came back. I had to sleep sitting up. It has been three days and whenever I wake up, my head feels so heavy and I have to get up slowly to prevent myself of getting dizzy. I also started to realize that my allergies have been acting up lately. They haven't acted up in a couple of months, but once they did, I started to get dizzy and have an upset stomach, too. Why is this happening?