hi there!!
to be honest, if you would find a good, well experienced sportsphysio that could be enough. its hard to say anything more about your problem, because this area is such a complex region with lots of small muscles as well as muscle tendons from lower leg area. also a lot of nerv tissue around, fascia and aponeurosis etc. also it is really important to c u weight bearing because the arch of foot and tho whole biomechanics are so important and can cause hundred of problems. so my advice would be forget aboutmri and injection(would only reduce problems for a short period of time) and try to find a good sportsphysio how has the time to sort things out. if that doesnt work out you can still do the mri etc.
all the best!!