I am not sure abt your other medical problems, but this pain can be nerve impingement causing pain going down to your left arm and hand.
OR it can be more serious condition. You are very young, but sometimes pain of heart attack can be similar to this pain. It can be associated with Difficulty breathing, lightheadness , dizziness , nausea and raise in heart rate. Or just PAIN. So go see yr DoCtor.
Would you like to video or text chat with me?