Pre-labor pain?

My body has been feeling very weird today like you know right when you get your period or are about to... my legs feel heavy and aching so does my stomach and back. Baby is 37 weeks has been active these few days more than usual. I’m not sure what contractions feel like but like to know if someone can describe the feeling and what do Braxton Hicks feels like? I think I’ve had Braxton Hicks- they feel like really bad foot cramps and tightening in the stomach? Anyways give me a good example of how early contractions feel like and how your body feels... Thanks