First, get it checked out by a professional right away. Hopefully, you'll rule out any major issues. A lot of times, if there are no structural issues, it can be corrected with physical therapy.
Until then, rest and ice. Your coach should want to know what is wrong and get it fixed. It is time to be smart, not a hero. Good luck.
This is right on. "Playing through it" usually results in something worse. The only change I would make is DON'T ice. Unless you have an allergy, use Ibuprofin or another anti-inflammatory. We all grew up with ice, but the prevailing opinion now is that always was and is a mistake. While it provides pain relief and helps with swelling, it also impedes blood flow, thereby vastly slowing down the healing process. Not to step on any toes.
Not to start an argument (or go off on a tangent) but I heard the exact opposite regarding ice. That it stimulates blood flow as the area warms up and the blood flow is what heals the area. When my kid was working thru is elbow issue, his trainer had him do various arm/wrist exercises, followed up with massage, heat via some ultrasonic thing, and finally ice. It seemed to work, but who the heck really knows.
I heard only ice if pain is present. When my son did physical therapy on shoulder a few yrs back the therapist iced it after 30 min workout.
Best advice here is to see Ortho dr. Not family dr. Go straight to specialist as they may need to follow in HS as need arises. Find the one that the colleges in your are uses.
good luck, keep us updated.