Thanks for the advice Canuck Physio!
What do you think of the injury being something like Bicep Tendonitis?
From the stuff I have read about it it seems to fit all the symptoms.
Anyway - taking a break from squash to recover. Today the arm is fine, there have been moments during the day where I have felt monor tweaks, usually during movement but not doing anything specific.
It seems the tender spot is the inside front of my shoulder - its not sore I know its there.