What Causes Amenorrhea, Stomach Bloating, Back Pain And Cramping With Discharge?

I haven't had a period in 2 going on 3 months, i've taken countless pregnancy tests that all have come up negative, but i'm feeling bloated and i've been having lower back pain and some cramping and a discharge.... should i have a blood test done at a clinic, and how long will it take to get the results?