In horrible pain only 16 please help?

Ok im 16 and have this pain in my back its right by my right shoulder blade near my spine its like a stabbing pain iv had it for months and it gets worse when i exersise or lay down.Iv had a X ray and MRI of my spine and a chest xray that were all negative.I dont know where else to go..the pains annoying what other test can i do to find out whats wrong...if its not my spine or lungs what the heck is wrong?? Also my neck is also painfull and stiff