callus on thumb

Question
Hi, Chip, need your help., im developing a callus on the side inner part of my thumb,almost on the knuckle joint,  im right handed, pitches are: fingers 1/4 lat left, 1/2 lat right, 3/16 rev, thumb 3/16 rev -0-latertal, span 4 3/8, 4 7/16.

thanks,

Isaac

Answer
I would make sure the span is not too long, although I would think that would cause some issues at the base of the thumb too.  
I would check th size of the thumb hole.  The placement of the callous suggest squeezing.  I do not think you have excessive pitch in your thumb hole.

Good luck,
Chip