Heel pain in adults is due to many different conditions, however the most common cause is a condition known as plantar fasciitis. The pain from plantar fasciitis frequently occurs under the heel and the classic symptom is that the pain is even worse when getting up first thing in the morning for those initial few steps. Following those first steps the discomfort does typically ease considerably, however gets worse again as the day goes on. The plantar fascia is a long ligament under the bottom of the foot that is responsible for supporting the arch of the foot, so plantar fasciitis is caused by there is excessive force on the arch of the foot. The key risk factors for plantar fasciitis are tight calf muscles, being obese and having higher levels of exercise. Foot dysfunctional issues that increases the load in the plantar fascia can also be a factor in increasing the strain.
The first approach to plantar fasciitis is pain alleviation with the use of ice following activity and maybe using anti-inflammatory as well as pain relief drugs. Taping could also be used temporarily to help with the pain. Foot orthoses could be used to decrease the strain on the arch of the foot and fix any alignment issues that might be a issue in leading to the plantar fasciitis. You will need to stretch the leg muscles as this is a major risk. Splints to wear at night can also be used to assist with that stretching if necessary. Strengthening the muscles which also support the arch can also be of great benefit because they take some strain of the plantar fascia. Over the long term, weight reduction is essential since this truly does create a lot of strain in the feet. If these kinds of approaches may not be helping to well, then it's time to consider things like shockwave therapy or corticosteroid injection therapy. A last resort would be surgical treatment.