Lump on Right Foot

I have had a lump on my right foot for a long time.
Its located more to the side.
The pain can be very excrutuiating at times.
I had an MRI done and went to a podiatrist.
He told me that it was a lump of fat and he wouldn’t do surgery because it could come back in 10-15 years, and would scar my foot (which I wouldn’t care).
He first subscribed a medrose(?) pack, which because of the steriods in it, made me hyper.
Afer that since it didn’t work, he put me on celebrex, which after a day of taking made my feet swell up and caused an awful stomach pain.
I discontinued the use of celebrex and stopped going to that doctor.
He told me with excercise the lump would decrease, so through the pain I have forced myself to excercise the foot in any way I could.
But it had not deduced in size, if anything has looked like it has gotten bigger.
What is this lump that hurts so badly?
I plan on going back to a different podiatrist, but until then, I want to know if the other one has misdiagnosed me.