Heels are one of the places pressure sores form. Pressure sores tend to form where skin covers bony areas with less tissue under the skin to pad the area. These include the buttocks, elbows, hips, heels, ankles, shoulders, back and back of the head. So for most heel wounds, the signs of infection to watch for are the ones for pressure sores.
Contact your provider right away if you develop blisters, an open sore, or any signs of infection, such as a foul odor from the sore, pus coming out of the sore, redness and tenderness around the sore, skin close to the sore that is warm or swollen, or fever.
Don’t skim past the first part of that. Blisters and a new open sore are reasons to contact your provider on their own, before any sign of infection appears. On a heel that matters, because a stage II pressure sore is skin that blisters or forms an open sore.
Check the skin around the wound, too. A stage I pressure sore is a reddened, painful area on the skin that does not turn white (blanch) when pressed. Redness that stays red when you press it is a sign that a pressure ulcer may be forming. That is different from redness that turns white and then comes back.
One more thing about heels, which are often covered when they are wounded. Some sores are covered in dead skin that is yellow, tan, green, or brown. The dead skin makes it hard to tell how deep the sore is. This type of sore is unstageable. If your heel wound has that covering, neither you nor a photo can tell what is underneath it. Be sure to mention it when you describe the wound.