Day 67 - First injury?

Day 65, friday afternoon, while sitting on the couch, I had a sudden pain in the sole on the outer side of my foot between the ball and the heel. Initially the area was small and felt like the dull ache after one gets a thorn or needle or pin stuck in the sole. I checked the area but found nothing there, no needle or pin prick. I ignored the pain and went about doing whatever I was doing. By the evening, the area and intensity of the pain had increased. I checked the web, but didnt find anything helpful. Had to take ibuprofen for the pain.
Next day, was slightly better, but hurt when I walked. Walked with foot tilted towards the inside i.e. pronated ;), wow, have started using the running terminology.
Today, much much better, but didnt go for a walk or run as didnt want to aggravate the injury. Hopefully, things would be much better tomorrow, and I'll go for a walk atleast if not a run.
Was thinking, how much a small injury can affect your schedule. I still don't know what the pain is all about as it didnt occur when I was running, but started around 20 hrs after my last workout when I was sitting on the couch :(