Suggest Treatment For Pain In The Shoulder And Lower Back

my shoulder started hurting sudenly and has gotten worse with time; the pain comes on sudden and strong but comes and goes. i didnt lean on it or sleeped weird or hurt it during any activity. when i take a deap breath it hurs only on my back towards the bottom of my scapula (this is what i mean by shoulder/back) when the pain comes it is gradual the first day it only hurts a little on my back by the second day it hurts lots specially with movement of arm pulling doors open and so on. it is also very painful at this point to turn my head in any direction side to side up and down. i injurded my lowerback about a year ago. i feel extream pain in that area every once in a while i apply heat when that happens. im not sure if my back and my shoulder pain are related. i also have knee pain. i would also like to add that i like to go hiking often and my boyfriend was just diagnosed with mono. please help :( Thank you very much for taking time to answer my question :)