Buckley,
You have had this problem now for nearly 9 weeks, you have been having physio twice a week for the past 4 weeks, if this was a simple bicep problem it would have been resolved by now. Obviously this is more complex, the physio should get the Wikipedia reference-linkMRI just to cover his own backside. GO GET AN MRI. I send for MRI all the time, even if the scan comes back with diagnosis that the physio original said, it will do 2 things. 1) puts your mind at rest and 2) gives the physio a clear cut picture of what is going on and a time frame to work with, i still don't understand why practitioners don't use scans as often as they should.
C