@Alworadish,
Unless someone else posts, I think it is back to the vets for this one.
Could possibly be that the meds are interfering with the clear up of fluids, in conjunctive use or alone.
If death is imminent, if they just send you home.. a last resort which is conceivably bad advice, is to place a boiling water bowl with a towel over it on the floor with a small portion of bleach mixed in and let the dog breath it.. it might allow a clear up and a 'cough out' temporarily.
Tested on myself, lungs cleared up a bit. (heavy smoker).
Again, I know this is bad advice, but it is advice none the less.
Questions are no doubt - does it hurt?
No, it mildly feels odd. (a two or three minute spell at pure bleach in say.. 1 part to 100 water)