Am I pregnant?

I haven’t been feeling good since Friday, all of a sudden I had really bad shakes for an hour and been sick twice, I tried getting something to eat since I hadn’t eaten (grapes and a chicken salad sandwich) which took me a while to eat and eventually vomited it up, so I didn’t eat anything till later as I still felt poorly all day but managed to keep garlic bread down on the night, yesterday I just felt nauseous all day with a bad head (sensitive to light) I vomited most of my food up on the night but also managed to keep some down, today I feel nauseous with a bad head all day and shakes are coming back a little, I’ve had unprotected sex for nearly a year now, anyone have any ideas?