I had to look up Acromegaly. Was the surgery successful? (Pituitary tumor). The issues with your feet may be RSD related, did you have that before? It may have been brought on by the knee surgeries. It may be neuropathy of some sort. I have it as well, the burning red feet.
These are just some thoughts, I am not a doctor!
Let us know your rsd history, if any!

Wish you the best!

Pete