What Causes Vaginal Pain With Discharge And Odor?

Hey. I am 20 years old. 140 pounds. I recently had a uti that i didn't cure because i stopped taking the medicine. I believe that I have one now. my sides hurt as well as my back. I also have a strong smelling urine on certain days. I also feel pressure in my vagina area like something is up there or about to fall out. it doesn't hurt but it is uncomforatble. My boyfriend and I had sex two weeks ago and when i went to the bathroom to wash up, i saw that his semen coming out of me was yellow. This week when we did it the semen was still a little yellow but very light. I get a pain in my vaginal area when i become aroused. Now today i noticed that i have a yellow discharge. It has now smell. what could this be?