I had some achilles tendonitis recently and my physio suggested that you put some heel pads in your shoes when playing to lift the heel, it will reduce the amount of strain on the achilles.
It works well. I used the proper Sorbothane ones because they're firm enough to lift the heel sufficiently to stop the achilles over extending, rather than the foam heel pads that just turn to mush when you put your weight on them. Best to place them underneath your insole.
In fact the product description actually says;
SorbothaneŽ Heel Pads can also be used for the treatment of Achilles Tendonitis and other foot conditions, as well as preventing shin splints. SorbothaneŽ's total control top sheet contains advanced, antibacterial Nano Silver technology to kill bacteria on contact, wicking moisture away from skin and managing odour for optimal hygiene and comfort.