Hi.my Dog Developed A Lump The Size Of A Small

hi.my dog developed a lump the size of a small football around the side of his neck.we have taken him to the vet,they said it was an abscess..told us to put a hot compress on it,,hoping it will break,we have been doing that for the last couple of days ,its might be shrinking alittle because he is taking medication to,,but his breathing isn't the same,he snores more,plus he coughs and kinda like choking noise...and on the other side of his face is a small size golf ball ,,I think it a swollen gland the vet didn't sound to concerned with that..could you please help me..thanks