Your symptoms are very suggestive of Plantar Fasciitis. This occurs due to the fascia getting contracted due to repeated minor trauma especially in people who are on their feet for prolonged periods of time. This can be treated by doing plantar fascia stretching exercises. There are three main exercises to slowly and gradually stretch the plantar fascia to its normal length over a period of 4 to 6 weeks. These exercises could be explained in person by a Podiatrist. You may get them in the internet. Also with this, equally important is to use soft, pressure distributing insoled foot wear. Materials like Poron, Silicon, Platazote, E.V.A. are good. The may be used as inserts in your foot wear. Please continue with the prescribed foot wear to prevent recurrence of the problem.