Birds have feather tracts on their body which help to cover up bare areas... so some of what you are seeing might be normal.
Cockatiels are naturally dusty birds, so may sneeze a lot if it's dry and they get a lot of dander in their nostrils. Increasing humidity may help.
There are a lot of medications that humans, dogs, cat and even birds get - however, the concentrations they get varies depending on not only species, but size. *IF* human medication is given to our dogs, cats or birds (rather than using the equivalent geared towards said animals), then it's recommended to go with a medication geared towards kids. Adult strength medications may be too strong.
Sorry though, I don't know about the meds the vets prescribed.
Have you ever tried using this website to search for an avian vet? There might not be any local to you, but it might be worth a shot?
Member Search - Association of Avian Veterinarians