After being sick you don't need antibiotics. Your ENT should have their head examined. Also, Musinex DM includes something to control couch which you're not having so it's overkill for you.

Netti pots don't work on ears now do they? Really bad advice.

If you travel a lot, throwing a decongestant in your bag isn't a bad idea. Better to have and not need.

It's a fine line in using something to clear up congestion. They can overdry your mucous membranes so you need to typically use less than the desired dose. It's idea if you play around with them before the flight. Essentially you want as little as possible to ease the congesion.