Could The Spotting In The Mid Of The Cycle Be Implantation Bleeding?

I am 22 and my husband is 21. We recently decided to try to have our first child. A few days after my period we started having unprotected intercourse; always fairly gentle so no trauma. I started cramping for a few days and then the third day (two weeks before my period) I started spotting lightly just when I wiped. Since then it has progressed into a very very light period (much lighter than my regular flow) . It is mostly very very dark with clots. This has gone on over a week and Im still having minor cramps. At first I thought it was implantation bleeding but it seems to have surpassed that possible reason. The three pregnancy tests have been negative. I have some pregnancy symptoms such as hightened sense of smell, frequent urination, gums bleeding when brushing my teeth and sore joints (knees, previously no pain prior). I have an appointment with our doctor in a few days but this is worrying myself and my husband a little. I was curious for any thoughts. Thank you :)