I had my well motor replaced about 4 years ago... since no problem
Had my well motor relay box replaced a year ago... since then, no problem
Now, when running a tub, water runs for about 4-5 minutes, shuts totally off and then after the same length of time runs again... etc. etc.
Clue: I was outside today, and I noticed the water from my patio bib was on, and the hose was TWICE its normal size!
Don't know if this is all connected to the same problem, but the local plumber wants 500.00 to come out and fix it.

I was outside today, and I noticed the water from my patio bib was on, and the hose was TWICE its normal size!
Well of course it was twice the size. Assuming a light weight vinyl hose with 40 to 60# of pressure, laying out in the sun to hot and weak, of course its going to swell and burst. Has nothing to do with well.
Assuming you have a bladder tank, press the needle in the valve stem and see if you get air or water.
Quite likely you have a rupture bladder and water logged tank.

Could very well turn out to be the tank, but that's strange for water to run fine for several minutes and then just completely go to nothing for any length of time. A bad tank would more normally have the pressure running up and down in short cycles of several seconds. Come back again if the tank checks out good.