Hello Im In The Army And When I Wear My

Hello im in the army and when I wear my Bergen I feel a burning sharp stabbing pain on my left trap/shoulder area. At first I thought it was just the pain from my heavy Bergen but now I realise this is not my muscle but more my skin/fatty part of the area. When I pinch that small area the pain is terrible. it feels like an infection or burn but there is no redness or swelling or any thing out of the ordinary. The pain has been going on for 5 yeats but I only get it when I wear my Bergen. It normally hurts for a few days after but when I pinch that area the pain is all the time