Welcome, rkjb1951.
I wonder if you've been checked for diabetes? Quite often it causes the symptoms you describe.

Since you have a cardiologist, my guess is that you were tested for diabetes and that wasn't the problem.

How about spinal problems? Often our backs start to wear out as we get older, and degenerative disk disease and arthritis and other aging "issues" set in. They can cause a boatload of symptoms.

Are you make sure you have the right kind of shoes? For years I bought the cheapest and most comfortable shoes I could find--canvas sneakers--but began to be troubled by back pain and other problems. When I was told that I needed shoes with better support and got them, a lot of my problems went away.

It's just a thought. I hope you can find some helpful answers.