Pain/pressure in lower left and right sides by hips? Really worried:(?

I've been having this weird pain/pressure in my sides for 2 weeks now and its gotton worse this weekend. It started just in my right side, now its moved to both and I sometimes have back pain at the same time. I'm really worried and I don't know what to do! I've told my parents and they keep saying 'you'll be fine' and it's so annoying cuz I'm stressing out so much! I can't go the doctors on my own, it's a 20 minute car journey, far too long to walk, plus I'm only 15 year old girl and don't have the confidence to go alone. Could someone please tell me what could be wrong?:(