5th metatarsal continued pain

This is a bit of a long story, but went to see three doctors and the first sent me for an xray that he said didn’t show bone injury. Went back and another doctor said xray unclear and sent for another from which he identified small fracture and gave me crutches. On follow-up appointment they had lost second xray and another doctor told me it was impossible for it to be fractured and not show up on first as it was clear.
I’m going to uni in a week and finding it very painful both on surface and underneath my foot after long walks or any reasonable exercise. It’s still mishapen and bruised 7 weeks later. Any advise on what to do with it and which doctor is right?