Hi, I'm 18 years old and i often have really bad sharp stomach pain, sometimes lower back pain, chess pain here ans there, and in march i didnt have a period. This has been going on for about two years. I've seen a doctor a year ago and they thought it was due to eating habitats so i changed it but its still happening. Also i am sexually active. I don't know what to do or whats wrong with me. If you coukd give me your opinion that would really help.