I don't know if i should go to the doctor. i think i have swimmers shoulder but i'm not sure and don't want to waste money.

Shoulder pain: At your age good exercises should allow it to resolve. At the most you need good PT

SHOULDER PAIN: "Swimmers shoulder" loosely describes overuse and impingement syndrome's seen in nearly 35% of competitive swimmers. Successful treatment involves accurate diagnosis, identification of the injured elements of the joint and rehab that typically occurs in the seven stages to treat inflammation and then re-stabilize & strengthen the joint to prevent reoccurrence. I'd recommend orthopedic follow-up

Ok: Well, swimmers shoulder is not life threatening. You will ultimately have to decide whether or not you are having enough trouble with it to be "worth going."