Random Achilles Pain...

47, 6ft, 325lbs, Male, Caucasian

For the past 5 or 6 years, I wake up occasionally, obxe or twice a year, with a random achilles pain.

It always develops overnight while I'm sleeping. Always just one side. It hurts when I put pressure on it especially, but also hurts even if Im just resting. It feels like someone is constantly pinching right where my achilles is.

Does anyone know what it could be, what causes it, and/or how to prevent it?