Toxic Mouth Discharge & Licking

I would greatly appreciate it if anyone can help me. My twelve year old Cocker Spaniel continues to deteriorate inspite of doctor's treatment. For about eight months he has had this toxic saliva that makes him lick his paws, legs, stomach any anywhere else he can reach. I can't get him to stop licking. The saliva, which at times drips in strings from his mouth, is foul smelling and very toxic to his skin, causing it to get very red and raw. He coughs, almost chokes, up the clear, thick saliva. It even appears to be making his mouth raw and he is having great difficulty eating, just holding the food in his mouth.

The doctor said he had heart problems and gave him Furosemide and is treating him for liver problems and has him on Adenosyl, Thyrosyn and Amoxicillin for an infection. He recently ruled out "Cushings" disease.

Does anyone have any ideas; his condition continues to worsen and I feel like he has been mis-diagnosed.

Find another vet for a 2nd opinion and fast. :/

I agree, a second opinion would be a good idea at this point. Go with your gut, if its telling you something is off, then run with that.