Backache after one week of intercourse during ovulation period

After scheduling a session around ovulation, we had sex a few times but nothing was done about it. I think maybe we were too young and not ready to have kids. However, in the last week, I have experienced backache, which makes me very worried.

I started to worry that I might be pregnant because I had been missing my period for a few days. I was worried if I had an allergic reaction or if my backache was caused by certain foods we had eaten recently.

I consulted the doctor, who told me that my backache may be caused by my partner using too much force during intercourse, or by my high protein content. The doctor also told me that if I still feel sore in my back in the next few days, I should check to see if I am pregnant.