What could be the reason why my heels hurt when i walk?

Plantar fasciitis: Plantar fasciitis would be the most likely problem but it could be a fracture.

Plantar fasciitis.: The most common cause of heel pain is plantar fasciitis: an inflammation of a thick band of tissue that helps hold up the arch of your foot. It attaches to your heel bone, and is usually the most painful during the first few steps in the morning, or after sitting a long time and then standing quickly. Check with your podiatrist to rule out nerve damage, stress fracture, or other bony problems.

Heel pain: When you have pain at the heel, it could be from several causes. Most common is plantar fasciitis, other causes are stress fracture, nerve impingement, flexor hallus muscle belly inflammation, fat pad atrophy, systemic inflammatory disorders (anklosying spondolitis, reactive arthritis syndrome, etc). Hope that answers your question.

Could be...: Plantar fascitis if the pains occur mainly in the heel area and even possibly the arch. It could also be generalized arthritis and a number of other possibilities. Take the insoles out of your shoes and replace them with ones that have more arch support. The one i recommend most is the spenco polysorb cross-trainer insole. If you don't need as much cushioning, the total support is also good.