I'd also check your arches...I had pretty flat feet in general, and every time I played intense basketball or sprinted or did anything aerobic, my heel would absolutely be wrecked. It felt sensitive, and like there was lead inside. Just was really heavy and anytime any regular pressure was applied (while walking), it would just flare in pain for hours afterward.
Long story short, I had custom orthodics made to give me some support and slightly correct my arches. Worked wonderfully, within 2 weeks I was pain-free (and have been for 3-4 years now).
Just something to check on.