I have had a post nasal drip for a few months. it has gotten better but an ent dr. wants me to do a barium swallow do i really need this?

No: A barium swallow is for difficulty or abnormalities with swallowing. If you had post nasal drip which has resolved, and you do not have swallowing problems, then a barium swallow woud not be useful. You should return to your ENT to discuss this further, in case there is more going on that your ENT is concerned about.

Probably: Without a lot of information, i would suppose that your ENT thinks the symptoms are from acid reflux and is checking for it.