Plantar fasciitis can cause heel pain. There is a fascial band that originates at the bottom of the heel. Sometimes the band becomes tight and can cause pain when you stand for extended period of times. If you have flat feet, the band tends to overstretch and become painful with prolong standing.
Another cause for heel pain can be nerve entrapment. I would have the heels x-rayed to rule out any tumors or bone irregularities and have the foot evaluated. Orthotics, cortisone injections, and stretching the calf muscles can help.
Thank you VERY much for your response. I will have them x-rayed!