Pain under the heel that is worse in the morning is almost always due to a condition known as planter fasciitis. That morning pain is sometimes called post-static disc can easier, meaning that it is painful after rest. The most common cause of planter fasciitis is usually flat feet. There are many causes of flat feet, but most will need some sort of foot support to manage them. There are some credible sources of information on the web about planter fasciitis but there are also some incredible resources on the web that are not to be trusted. If you have planter fasciitis you really need to be treated by someone who knows what they are doing.