plantar fascitis is usually caused from inflamation of the plantar fascia muscles being stretched over the heel. Normally the pain is from thing such as spurs (mineral deposits) irritating the muscles when you put pressure on the foot. Shoe inserts can help, also use things such as ibuprofen, but as stated in the other posts, stretching can GREATLY help. The professional treatments are the 3 following
1-shoe inserts
2-steroid injection
3-surgical removal of the "spur", which can return over time

I personally have had flair ups here and there.........usually changing shoes for a while and STRETCHING the foot easily fixes the aches with in a day or so