Switch Grip for the thumb?

In addition to dietary issues, like too much salt, sometimes a wrist support put on too snugly will cause the thumb and fingers to swell enough to be a problem.  I have a forearm support, like the ones for tennis elbow, that will cause swelling in the thumb if I have it too tight also.

Like you, it takes a game or two before it happens.  What I do is squeeze tightly my thumb for a few minutes and the thumb gets back to normal size.  That usually is enough to get me through the night until I remove the support(s). 

My friend has a thumb insert (smaller size) that he keeps on his thumb 5-10 minutes before he bowls to get the thumb to it's normal size.  His thumb is usually swollen before he starts bowling. 

Look at it this way.  As we use muscles they tend to swell until they cool back down.  The only muscles where minimal swelling would be noticed would be the thumb and fingers in bowling because we have them precisely fit, and usually not right after bowling when there could be swelling.  Diet can contribute, but sometimes it has nothing to do with it.

On a sidenote, all my thumb holes have room for at least 4-7 pieces of tape for that reason.  I can always remove a piece or two...

As I was editing my post, charlest was on the exact same thought process.  Sick minds think alike?

I have three different sizes thumb IT and the idea of keeping the thumb inside a smaller thumb IT sound like the towel trick.

I don't use any wrist or hand devices, and for tape, I use Magic Carpet on the back and 1 to 3 white tapes up front. I think the rubbing of the magic carpet tape is a factor too.

For diner, I had had half a bowl or two cups of tomato soup, half a turkey sandwich, and two 1" squares of pecan pie 4 hours prior to leagues. I bowl at 9:15pm.

but my diet isn't healthy too...