What Causes A Dull Pain In The Lower Left Rib?

Hi there, I'm wondering if I have slipping rib syndrome. I have suffered from a dull pain in my lower left rib cage since I was about 14. Every so often it gets worse and my breathing is affected as well as my left arm feeling weaker. I went to the hospital when I was 14 as my breathing was severally affected and they gave me antibiotics for a chest infection as they couldn't find anything else wrong with me. It didn't really go away, only getting duller at times, and becoming more painful and heavily affecting breathing at others.. I have been to the doctors a couple of times since (I am 22 now) and had an x-ray, they have never really given me a satisfactory answer. After googling chest pain and rib pain I found slipping rib syndrome and it seems to fit. Does this seem like a plausible diagnosis?