over heating and nauseous

Ever since I got pregnant (thankful I did) I've been having a really hard time with over hearing constantly. In order for me to cool down I have to sit in front of a fan for 20 minutes or put ice packs or cold rags on my neck and chest. This over heating is making me very nauseous and dizzy. Is anyone else having this issue? It's actually scaring me. We haven't had our first ultrasound yet and I'm just praying everything is normal.