Not sure if this could be the cause for you but I went through a similar issue, surprisingly changing to a new shoe with a good sports insole fixed my problem. The same way one of my friend in my club also was able to fix his heel pain.
Go to a doctor to have it checked. But you can go ahead and change your shoes first, and you can also purchase good insoles. I've heard that the Spenco total support is good, but it has a lot of cushion so you might feel a bouncy feeling in the court which will slow down your traction. I am using Superfeet and I love it. It heals my heel pain and knee pain. I posted my review here. Hope it will help you.