What Causes Abdominal Cramps Along With Along Wit Abnormal Vaginal Discharge?

Hey about 11 months ago I got on the birth control shot the 3 month one and didn t end up having my period till the 27th of last month. I wasn t sure when I was ovulation so my boyfriend and I had intercourse to try and see if I get pregnant cause I am not sure if I can have another baby. It s been about 2 weeks now and I been having really bad cramps and have gained 8 pounds in 4 day but other than that I have been having a very white creamy but chunky discharge and it only has a smell after sex. What do you this is wrong?