Help. weird symptom? anyone else?

I'm 21 weeks pregnant, and get really bad dizzy spells. The thing is they happen even when I'm just sitting or laying down. the dizziness feels like I'm floating up (if that makes any sense) and the room starts spinning then my vision goes blurry. I know there's low blood pressure in the second trimester, but it also scares me because it reminds me of the feeling I got before I'd have seizures when I was little. Not sure if I should worry or not. I'm going to try to remember to bring it up at my appointment on Monday though. Anyone have similar experiences?