I crashed a 4 wheeler and screwed up my collar bone on my right side and have been told not to lay on my right side because it is too hard on my collar bone. Mine doesn't make noise or pop or anything but if I wake up and happen to be on my right side my collar bone will hurt for a while afterwards. I got to Massage Theropy and a Chiropractor for that and my back and helps a bunch. That could be something to look into.
I can't tell you what's exactly wrong with you but because you can't sleep on that side in comfort and your other symptoms, suggests there is a problem. You may have damaged/torn a tendon, I have these symptoms because I completely tore a tendon in my shoulder and I'm waiting on keyhole surgery. I hurt my shoulder at work in May and it's now October - it hasn't healed because tendons won't reattach to the bone by themselves.
Your doctor will do all the tests to find out what is going on, you may only need physiotherapy but if you do need surgery it will only be done out of necessity. Having your shoulder repaired surgically is better than putting up with what you are now? You're only 13 and you have a life time ahead of you using that shoulder, it's better to fix it now than let it get worse.
It might not be a tendon, it might be something else and your doctor will be the one to find this out. Good Luck. =)