Tried hard to please coach. Now I feel like crying all the time? Knee pain is keeping me out of sports.

Get it examined. From injury to illness, it is not fun to feel knee pain. Damage to the soft tissue like ligaments or tendons, fractured kneecaps, gout or arthritis can all keep you from walking, and can become worse if not attended to. Again, get it examined. As for the dysphoria, you may also want some therapy to help cope with having lost some function, such as walking or sports activity. Get help.
Please remember. that your physical health and wellbeing are more important than pleasing a coach. If this has not been medically evaluated - would recommend that. The medical provider can determine cause of your pain & recommend treatment & restrictions. Any good coach should respect medical recomendations. Heal Soon.