The possible diagnosis could be fracture or any bony growth.
The symptom of pain
at the bottom of foot
suggests that you might have a stress
fracture, Calcaneal bursitis, or retro-Calcaneal bursitis.
You can get X-rays, including AP, lateral, and oblique views, should be obtained, but it must be remembered that X-rays may not show changes for up to 3 weeks after a stress fracture. Bone scan and MRI may help confirm the diagnosis and may be positive as little as 2 days after stress fracture.