Hun-- call a local Vet-- there MAy be sores or skin problems under the matted fur... they can give him something to keep him calm (no need to scare him) and then shave him, and treat any nicks, abrasions, bugs etc.. that may be under there.
Let them know this is a rescued cat-- they may be able to either give you a discount- or point you to someone who will do it for free!
Good Luck
Let them know this is a rescued cat-- they may be able to either give you a discount- or point you to someone who will do it for free!