Unexplained, crippling pain that alternates between L&R foot

I’ve had episodes of pain over the past 8 years that are increasing in frequency. It usually starts as an ache near the TMT joint or a tightness of the plantar fascia in the middle of the arch of my foot.
It seems to be aggrevated by walking on it and if I do, by the end of the day my foot feels like all the joints are locked up,slightly swollen but very painful. If I try to walk without bending the foot, my whole legs gets sore.
It happens in each foot but never at the same time, sometimes it just happens to one foot and then goes away for months, other times it moves from one to the other with a few days break in between.My doctor gave me naproxyn sodium but it doesn’t seem to help much. I had similar symptoms a couple years ago in one big toe was suspected to be gout but uric acid levels tested normal. I would be grateful for any advice. I’m 46 and otherwise healthy.
Thanks, Curt