Roger, I installed flooring for 25 years too and have exactly what you have now myself. It has been a couple of months now and it gets progressively worse, but comes and goes in degrees, but never goes away completely.
I don't know what it is, but the tendon?, or long muscle that runs behind the knee is somehow involved and if you grab it with your hand or put pressure on it, it seems to cut down on the pain. It seems to progress up into my butt and kinda has some sciatica pain and all the way down to my ankle and foot.
I am going to see a doctor, but I have too much to get done before winter, so I have been sucking it up. It is painful as hell though and taking pills has not touched it. Those 800 mg Ibuprofen are not good on the stomach of throat so beware.
I am 70 years old shortly so there is that. I would love to hear what your doc says when you go and will let you know how it goes for me.
Good luck
