Please help.... sharp pains begining in my back and going down my vag area tmi sorry....?

I am 21 weeks pregnant with a little boy and I have been spotting for a few days but I think that's normal today I have been having bad pains In my pelvic area and vaginal area it starts In my back and continues to my vaginal area my stomach gets very hard and tightens and i can feel something that feels like a tightening then loosening like contractions but I think it is a bit early to have brackten hicks contractions what should I do I'm worried?