im going to try the frozen can next rather than a bag of peas

Don't use cans of soup, use beer cans. Have a ready supply of cold ones and stick one under your foot. Once it starts to warm up, crack it open, get another cold one, stick that under your foot and drink the open one. Rinse and repeat. I guarantee you that one way or t'other the pain in your foot pain will disappear!

Fascia is like a continuous web that envelopes the entire body and everything in it. Quite often the pain we feel is often a result of tension as elsewhere in the myofascial system (the muscles and fascia of the body) usually resulting from an injury, trauma or posture. Quite often people (and therapists) will just treat the "pain" or area of the pain but not always the cause. So the pain will go away for a while, but its quite common for people to have the same reoccurring injury over and over. They rest until the symptom eases and then go straight back into the pattern of disfunction. If its got to the stage whereby its affecting your training, and you can afford it, I'd definitely see a therapist that specialises in fascial work.
Gavin King
Follow me on twitter @taichigav