MR, a physio will most likely send you for x-rays anyway, same as a dr (I'd hope), just to rule out a breakage. Might be worth popping straight up to your local hospital if you can, where it can all be done at once. If you go during the day it's less likely to be busy and you might not have to wait for hours. (This from the person whose twice had to go to hospital for foot/ankle issues - one a very bad sprain and one a broken foot). Hospitals also have a physio dept so if you're lucky you might be able to cover all bases.

If you doubt it's serious, I'd go to a physio, if you know a good one. I've never met a GP who seems to know what to do with joint/muscle/bone issues as well as a physio.