My dogs ears are disgusting they smell horrible to. what can i do to stop the smell?

ok i have a german shepard mix and the inside of his ears are completely filled with waxy brownish stuff that smells horrible i have tried to clean them out befor but he wont let me they are getting worse and i cant afford to take him to the vet. he also never stops scratching at them and he has made them bleed i dont know what to do for the poor thing. and he has a skin problem too. i think he might have alergies. can a dog be alergic to cats or dust mites?