Got surgery on 5th metatorsal for fracture. was off foot for 15 weeks total. but had cast on for 6 weeks. got cast removed now when i stand up i get severe pain in heel?

I am not going to assume you have had an extensive rehabilitation program because that’s what you require. 15 weeks of nonweightbearing without rehabilitating yourself you can expect all kinds of aches and pains. You require to see a physical therapist to help with the range of motion and strengthening. Without rehab you are doomed for failure. After an appropriate time you need to be followed