Pain on the outside of my foot

Mate, I'm no expert, but I had a similar experience over a year ago. Then it started comming on stronger as I up'd my miles running. Extended into the outside of my calf. Went to a Physio, was told a muscle strain. Carried on, grew into tight hams and glutes, finally ended up as a disc issue lumbar spine.

Might be nothing to do with your back, but I never even considered a back issue would be signaled by a pain in my foot, but thats were the nerve travels to.  I began to get sciatic pain, but also made no connection to a disc issue (as stated, no bio-mechanic expert)

Could be a totally left field bit of advise, but I'd get it checked out, they can do some simple checks to rule that out anyway.

Cheers