could also be a heal spur i had to have one removed from my right foot.
I get something similar google foot pain, up comes a pic of a foot you pin point whre the pain is, I got a few ideas from it, could be a nerve Impingement(Trapped Nerve) Plantar Facilitus ,the lump could be a ganglion, I take advil,put an ice block on it, I have had mine a couple of weeks or more, someone suggested I find more foot support for my shoes Orthontics stores sell shoe inserts. Good luck
may be just a plantar fasciitis.Physiotherapy would help.