Sure can relate to this problem because I am very vulnerable to ear/nose/throat problems.
To keep your cold out of your chest, use gravity. At night, when needed I arrange pillows so that I sleep on a bit of an incline, with my head and throat lower than my chest. If a cold is really in there deep, it takes 2 nights, but after only one night it already feels more like bronchitis, higher in the chest than it was the night before.
I'd be extremely cautious about combining any anti-fungal with an antibiotic. About a year or so ago, there were reports of the heart being severely affected by combining the two. Nystatin is supposed to be inert, but to be on the safe side I would not combine the two treatments anyway.
Probiotics don't live too long in the gut anyway. If you need the Antibiotics , go ahead and take them, but "chase" them with probiotics later. Of course you wouldn't take them at the same time... yeah I know it's like "duh," just saying so because when I'm sick I don't think straight, so there's a reminder. Also, if I am taking Antibiotics I am very careful not to feed the yeast. So, for me that means ONLY meat/fish, water and veggies.