What Causes Missed Periods With Lower Back Pain And Bruising In Pelvic Region?

Hi I have missed my period and it has been three months now and I have lower back pain and I feel pressure in my legs and I noticed the other day I had a bruise on top of my skin in my pelvic region I am very worried. I went to my pcp and she did a pap smear and checked for diabetes and my thyroid as well I havent got back the results yet but I am worried I am 26 years old I have had an increase in weight rapidly within a year about 30 ibs and I dont understand why.