Read ALL of this
https://www.mayoclinic.org/symptoms/...s/sym-20050942
You can ignore torsion and any other condition that would be obvious just from looking at your body, or cancer or anything that would have shown on the scan.
Doctors typically adopt a wait-and-see approach to pain. 2 days could just mean that you strained a leg or groin muscle and the strain is affecting a nerve to your testicle. He was extra thorough by sending you for a scan so early. Another typical cause might be a urinary infection, but it would usually sting when you urinate.
Masturbation has nothing to do with it, as he told you. Take the pain killer, and get some ibuprofin at a drugstore, and wait a week before calling the doctor again, if you still have pain. Try soaking in a hot bath every day to relieve any muscles that might be strained. Press all around your abdomen and left leg to feel for sore muscles.