Hi Cheryl,
Sorry for the long delay in replying!
Almost invariably for cats like your patient, I end up using San Ren Tang and changing their diet to some sort of 'real food'. Nutritional balance is not important for the first few weeks, so much as trying to find something that will stimulate the appetite while not being processed. As he feels better, we can get more picky about the diet and start tweaking it in the direction of balance. Canned fish, roast chicken from the grocery store, even freeze-dried grain-free diets (not constituted) are all options and will provide a foundation for San Ren Tang to hopefully do great things.
Regarding the current protocol, if he has improved on it, then there may be more room to improve. The problem is that the two formulas negate each other. Huey's Formula, which is actually the classic formula Cang Er Zi San, dispels acute Wind Heat while Bu Fei San 'locks the thief inside the house' and seals the pathogen in. One deals with drying discharges, the other creates a bunch of moisture. I would suggest stopping the Bu Fei San while adding in the San Ren Tang. The CEZS and SRT will work synergistically then, particularly if the diet is also changed. I use this combination in people for the identical situation.
If, for some reason, he worsens, then it is the tonic (BFS) that he needs, in which case you would stop the CEZS and SRT, and go in that direction instead (coupled with something else - maybe a Blood mover like Xue Fu Zhu Yu Tang). Given his age, though, and the nature of the discharge, I would be surprised if diet change + SRT +/- continued use of CEZS didn't resolve the problem or at least markedly improve it over the coming weeks
Steve