What Causes Painful Vagina And Delayed Periods?

Hi im 18 years of age and i have a serious question to ask. Well i havent been sexually active for at least 7 months now and my period hasn t came on so i had went and took a pregnancy test and it came back negative. but my question is if im not pregnant what hasnt my period been back on yet. not only that but i feel movement in my stomach, lower back pain, bigger breasts, and when i walk, sit, or try to lay down my pelvis hurts like hell. help me