If you have pain in the area shown in the picture, which is to the side of the heel, as opposed to the back, then this indicates you have inflammation in the bursa. A bursa is a fluid filled sack that sits between the Achilles and the heel bone to absorb the friction.
The bursa can become inflamed and damaged, sometimes on its own, sometimes with the tendon as well. It is often caused by tight calf muscles which pull the tendon harder onto the bone as you bend the ankle. It can also be caused by the shape of the heel bone.
A bursa will almost always be irritated by heel rise exercises, especially those dropping below the flat. Ice and rest is a better option to start with and get it assessed.