I need help! Am I pregnant?

OK, so I haven't been trying to get pregnant, I've actually been in the process of losing weight, but Anyway, I had a period the ended at the beginning of last week. At the end of that week I randomly got really nauseous. I lied down and the next morning was fine. I thought it was odd, but didn't look too much in to it. Then this week, I noticed I wasn't losing weight though I was sticking to a strict diet and workout routine. I usually lose several ounces a day, but for 3 days straight, I stayed the same, and actually gained a few ounces. Then I randomly got sick again, to the point of throwing up. Took a nap, and woke up alright. By this point I had a sneaking suspicious I was pregnant, though just thought, nah, not possible. Too close to my period, but to rule it out, I took a hpt. If I didn't have the funny feeling I was pregnant, I woulda thought the test was negative, but I looked real close and found a veeeeeeery faint blue line. I mean, it's itty bitty, but distinctly blue. Then I was like, well, I'll wait till tomorrow, and do a morning pee, and maybe the line will be darker. Took a test this morning, and it was completely negative. I'm thinking three possibilities. Evaporation line, early positive, or I actually miscarried and the positive was from lingering hormones. I just don't understand why I would start to get sick after my period. Can anyone help with this, or had experience with it? I'm really confused. I plan on waiting another few days to take a test. My last period lasted 5 days. Was very light, but there was bright red blood, and brown blood. No cramping. Thanks in advance!