Why did I have some bleeding after sex if my period was gone

My period started the 21 n it ended 25 I had intercourse w my husband n when I went to the bathroom I noticed I had some lite pink blood coming out, we have also been trying to get pregnant for about 6 months n nothing , we were having symptoms so we went to the clinic n the doctor treated us for chlamydia it's been more than a month since then. What r my chances of getting pregnant this month n why am I bleeding , would somebody plz help!