Braxton hicks

I'm a FTM. I've read up on contractions and such but just since I'm a FTM I'm still unsure about them and how to count them apart I think I understand.  Anyways I'm also unsure about Braxton hicks. From what I read I think I've been having them. I feel like I'm having period cramps and my very lower stomach feels like a cramp to kind of. I had it happen twice last night and now this morning. I'm not sure how long it lasts because since this is just starting to happen to me I didn't realize what could be going on. So I guess I'm just asking what Braxton hicks feel like, what's normal and not normal. And same with actual contractions. I'll be 29 weeks tomorrow.