What Causes Increased Pressure Above Vagina After Sex?

I am a 26 year old female. I have had irregular period since the birth of my 8 year old daughter. I am not on any birth control. I recieved one birth control shot after she was born and that was it. I took an at home pregnancy test which came back negative on the 14th of November and on the 15th started my period which lasted for 15 days. I've had a lot of nausea the past few days and although I am no longer I my period I just passed a small blood clot from my vagina and am having sever cramps, but am not sure what it is from. I have been cramping on and off for several months but just figured it was from the gastritis I was diagnosed with a couple of years ago. I had a pap smear done last week and expressed my concerns with my doctor. They said everything looked normal and was not concerned with giving me a pregnancy test and in fact told me that I won't get pregnant until I lose the excess weight. Another issue was that there was an increase pressure in the top of my vagina after intercourse.