Braxton hicks contractions

About every other day I've been getting some extremely bad pains mostly in my lower left abdomen sometimes they radiate to my lower back or all around my abdomen. I wasn't sure what it was from then I read about Braxton hicks contractions and was wondering when should I worry about them?? I see my Dr September 15th so of course ill bring them up then but I just wanted to know if I should worry about until then? Sometimes they are so bad I can't walk for a few minutes but switching the way I'm sitting usually helps or just relaxing for a few. I've felt them 3 different times today so far...