I'm feeling really sick and I'm alone. I need some answers?

Okay so I don't know whether this has anything to do with it but I have been a vegan for a month now. Today I went swimming at the YMCA and came home. It was a really cold walk out to my car. Immediately I started feeling kind of nauseous, and kind of like I had a sinus infection. I was so cold when I got home, even though the heater was set at 72 that I snuggled up to the radiator to get warm. I now feel extremely dizzy and sick to my stomach. Could it be the water in my ears? or is it my new diet? I can hardly walk straight and I'm by myself so I am a little freaked out. Some answers would be helpful. Also, I do not have a fever. I am just extremely dizzy and nauseous.