hi doctor,i havent received my periods for 3 months,ive done a home pregnancy test it was negative,took blood sumply from my doctor again yhe results were negative.He checked me with a sonar didnt find anything,also put his hand in my vagina & ask if i feel any pain & i said yes.Its he told me i have infection,gave me an injection & told me to bring my partner so that he can answer all my questions,all i need to know is what might cos this & how does it affect my mensturating cycle.