Spastic, quick fetal movements

I have been having my baby girl do some crazy quick movements. I have been calling her Thumper because it feels like that, like a whole bunch of quick hard movements so fast I can't even count them. Almost feels like baby girl is having a seizure sometimes and it's pretty scary! I have it happen to me at least once a day, and a couple of times it even woke me up in the night! Anyone else experience this? Any ideas if it's bad? I have an OB appointment in the next week, I'll ask him but I'm worried! Thank you!