Agree that if it is a cold, z-pack won't help. Assume you have seen a dr if you have that. If she/he diagnosed you with any bacterial infection, the z-pack should be working by now and so I'd return to ask for something else like augmentin. If just a viral infection, stop the z-pack as it won't help and just kills off all those good bacteria in your gut. If it is a viral infection, as others have said, the only thing you can do is let it run its course. Lots of rest and fluids, especially hot ones like tea and soup, especially any chicken broth ones.
As for the other things, I'd get some OTC meds like Mucinex or Robitussin, depending on your symptoms. Also I agree and highly second the Ear Planes. Follow the directions and work like a charm. I used them when I flew with a terrible cold and no ear pain at all. Also be sure to pack your own fav brand of tea. Nothing like still feeling under the weather and having no hot beverage options you like. Be sure to bring a couple bags on the plane too as you can always ask for hot water and use your own tea bag. Try hot showers too to steam up and that can help loosen the congestion. Finally, hand sanitizer! You're sick so your immune system is already dealing with something. Last thing you need is another bug on top of what you have.
Almost forgot -- be sure to take a decongestant right before your flight to help avoid uncomfortable degrees of pressure.
