PCOS (4 years) , PID. The cause of it?

I was having mild abdomen and lower abdomen pain and severe stomach pain sometimes. I went to doctor for the same. I had aborted my first pregnancy on 16 week 5 Years back. I have PCOD since past 4 years. I had irregular period earlier but now it is regular. As per doctor my body is not showing any effects of PCOD. Doctor has recently diagnosed me with PID and asked me to get admitted. I have only one sexual partner from last 4 years, but had physically intimated with many without any type of sex(no oral, anal or anything else). But i have stopped all these 1 year back and just been with my 4 year old partner. What is the possibility that my regular partner have STD? How to know since when i have PID? How to know who has infected whom, between me and my partner? How necessary it is ti get admitted to treat PID? Can abortion be the cause of it? I have attached Blood report,USG Report,prescription, and last year prescription as i was having abdominal pain with fever.