As per your complaint the possible cause may be the piriformis muscle tightness or trigger point, previously your sciatic nerve may be compressed that's why you are feel radiating pain from hip to heel. But in long standing pain muscle got trigger knot that need to be released. It may occur due to poor sitting posture or excessive cross leg sitting. Now you need to do hot water fomentation 2-3 times per day correct your sitting posture stretch your piriformis muscle. You need to visit your near by qualified physiotherapist for proper assessment and treatment. Wish you for good health soon. Thanks you