33 weeks. Strange fetal movement, rapid, twitching / jerking / spasm like movement?

Has anyone else experienced this? It doesnt happen a lot, but seems to happen in phases. And lasts a few minutes. Sometimes it feels like there is jerky, spastic movements, other times it feels like the baby is having convulsions. I have an appointment on Monday and I will ask my obgyn, but I would like to know if anyone else experienced this and if it is normal?