I just noticed a small, painless and firm bump above my inner ankle bone. it seems fixed. what could this be?

Cyst: could be a cyst? or maybe a fibroma (scar tissue). You would need xrays and MRI. Not to scare you but it could be a tumor. Most probably benign.

NEED A VISUAL.: Without being able to see it, it sounds like a fibroma. Only by seeing it and touching it would I be able to determine if a biopsy is needed. Follow-up with a podiatrist. Sincerely, Dr. Latva

Assuming its not: your tibia, it can be a ganglion. BTW, the fact that its not painful is irrelevant. a malignant mass does not have to hurt, it is advisable to have it checked out.