What are the possible injured tendons/ligaments in the elbow

Ok so my arm has been hurting for over 2 weeks now and I decided to go to get some help. I didn’t have an appointment at the time so I just went to the hospital because it was hurting bad. I described that the pain went from my elbow all the way up to my tricep to my deltoid. Note: I knew it wasn’t any type of joint injury and it wasn’t coming from the are where the tommy john surgery is.
So they took an x ray and didn’t find anything broken and said they would get me an MRI in a couple days, the doctor said that it was because of too much stress and overwork on my elbow so they gave me sling to keep my arm in one position until they got an MRI. The thing is I don’t know what the possible tendons or ligaments i could of hurt. The most pain is coming from my triceps and it hurt even after warming up. Please help.