I have had what feels like a knot like bump on the bottom of my foot by my arch and sole of my foot and it hurts to walk on. is it plantar fasciitis?

Knot: It may be a callus.Check with podiatrist for a definitive diagnosis and treatment.

Probably not, as PF-: Usually does not present with a swelling. It probably is planter fibromatosis ( benign condition), ganglion, fb (foreign body in form of a thorn, needle/nail, wooden splinter, with some infection around it) or rarely other types of cysts or lesions which are generally diagnosed with biopsy by the pathologist. Surgery not only rids swelling + tissue is available for biopsy, to ensure correct dx., .