It is most likely a little plant beetle / aphid type thing that just decided to take refuge from the elements But, if you think you have a pest in your mattress, get a bed bag - one of the allergenic ones will do well, and with little noise, and leave it on there for about 1-2 months and that...
I adopted a little stray kitten from a shed and he has pretty bad dry skin problems but I have never seen anything like you are describing.
Has he been checked for mange? I know mange causes crusty skin and hair loss in the area where the parasite is, if it continues to get worse or doesn't...
