Over worrying?

Okay so yesterday I was extremely sick, like puking,wanting to nap all day, non stop nauseas feeling... Then this morning I woke up and felt fine, I thought it was because I got 10 hours of sleep instead of 5-6 he's, but then I started to worry cuz of how great I felt out of all the other mornings having to bolt to the bathroom, but around like 9:30 the nausea hit me hard, I didn't puke tho.. I'm only 7 weeks pregnant, but is it normal to feel sick and yucky 1 day then the next feel nothing at all??? This is my first pregnancy so I don't know what exactly to expect. I just wanna make sure I haven't miscarried, I haven't had any bleeding but I have had some mild crampish pains??