Grade: 2
Blisters to back of heel, underneath heel and along the inside of foot. My toes also would tend to rub together cause irritation. I would also experience strain between the back of my heel and calf.
Been to a sports podiatrist who told me it was down to lack of flexibility and overpronation. I am now getting orthotics and have to stand on a positively angled surface for 5mins each day (equivelent to a breadboard set on two yellow pages) to improve my flexibility.
Get a new pair of shoes and tape yourself up before each run..