an ultra scan has revealed I have 2 frayed tendon,s in shoulder, plus a bag of fluid under armpit, you cannot see it, but feel it, and it is the size of a small plum,now they say I need a mri scan,which has come through pretty fast.could you tell me what it is, my shoulder is very painful to move, and the swelling under my armpit causes me to have pain to, also i have swelling round the ( mid arm) .i have had the trouble for 3 mths,had steroid injections first,but they did nothing .