Cough tastes like metal?

I had a really bad cough a few weeks ago, and it seems to have gotten a lot better. Occasionally now I'll have a dry cough, and my throat has "a tickle in it". Also every now and then I'll get this hallow sound when I cough in my chest, and starting today I sometimes taste almost a rusty taste when I cough. Could anyone tell me what could be wrong? I don't really want to go to a doctor because the cough has gotten a lot better.