I had a very similar problem to you by the sounds of it.
lots of physio sessions, lots of stretching of all kinds, lots of strengthening exercises and yet it keeps on reoccuring........
I can tell you how to fix it in one simple step - run barefoot. I strongly recommend buying Ken Bob Saxtons book to tell you how to do it correctly (virtually everything I found on the internet is codswallop, listen to it at your peril!).
My calf injury simply dissapppeared overnight.
I am now running up hills with zero problems and haven't even had a minor twinge from it. I spent about 4 months going backwards and forwards to the physios and wasted a lot of money. Spend £15 on that book and impliment what it talks about - I almost guarantee it will fix the problem and give you a real insight into how your body SHOULD be working. Going to physio's is simply going to treat the symptoms and NOT the cause.
Aferall the £15 for the book wouldn't even cover half a physio session....what have you got to lose.
Oh and it's really great fun