Pelvic pain. Could b the reasons for it?

I suffering from pain in left side of my lower abdomen.periods are very painful after taking pain killers too I don't get any relief. I need to know why there is sudden change in me.I always take all hygiene methods to keep my private parts clean however many times I hv been diagnosed with uniary tat infection.also at times there is vaginal discharge.sometimes the pain remains back after my periods.that makes me feel exhausted, tired and weak. I went to a gynecologist and she advised for a pelvic ultrasound for thyroid. I need to know can it b related to any tumors or stones in my uterus or ovary or it what. I am tensed and worried too.in addition to it I also get some discharge from breast which is white fluid and very minimal.I checked it by pressing them it's like half of a drop and transparent. Please suggest what could b the reasons for it?