My dogs breath is really bad?

bad breath
nolan’s Mommy asked:

Just recently my dog (he is a pug) has been having really bad breath. It almost smells like fish. He keeps licking his nose like he has something in his mouth or like he just ate something. Last night it looked like pus coming from his mouth when he was drooling. It might not have been from him though because it was only a tiny bit, but I looked and there arent any abcesses in his mouth and his teeth look fine. I really don’t have money to take him to the vet. Its been hot here these past few days so hes been a bit lathergic and he hasnt been eating as much. Could it be keytones like when humans are hungry?
Any advice is great