Once you bathe a coat that is already matted you have got a mess on your hands. If possible it is best to spray the mats with a good detangler first and then give a bath on a tangle free coat.
Amazon.com: The Stuff Silicon Dog Conditioner and... This spray has been used for years with pretty good success. I wouldn't use it as a regular thing but it is great for mats.
Once you finally get him mat free make sure you comb him everyday if he needs it or not. Even if you are going to keep his fur short he needs to learn to be groomed.
I'm not sure if your dog food has omega 3's in it but if it does not you might want to consider adding an omega 3 supplement to his diet. Also make sure when you bathe him that you rinse very well to get all shampoo and conditioner out or it can leave flakes.
When Gracie was a young puppy I usually had someone to help me when I had to bathe her or trim her nails (for her own safety) If you can't enlist anyone then just take it a little at a time. Hope you can make some headway on him. Sounds like you are going to need some extra conditioning with his coat and combing on a regular basis.