strange discharge, lower abdominal pain seems like water infection !

I have extermly strong urges to pass water recently and I pass very little which is strong and cloudy. I have sharp stabbing pains in my lower back, and at both sides of me under my bellybutton (like cramp pains) I feel sick all the time.

The strange discharge is a yellow/green colour which has a strong smell. There is no pain when passing water tho. Am very worried what this could be. I have been with my boyfriend for 1 year and we have unprotected sex, I have been on the birth pill since meeting him. He had a STD test a few month ago which came back all clear.

If I had a STD he could have had it wouldnt he ???

What would this be ??

Please help me !! Am just far to embarrarsed to go the doctors !!