Be seen. If you had sufficient mechanism to have fractured it and it is painful to bear weight, it could certainly be fractured. Consider being seen, an exam and appropriate studies will likely reveal the issue.
Need to look see. Micro cortical calcaneal fractures can occur routinely with severe cases of plantar fascia strain. Unless the heel is showing an obvious angular deformity and there is a traumatic or medically compromising reason for the fracture, there is just no way of being sure without some type of imaging.