There is no one by that name (or any variant spelling) in the records of the 37th Alabama Infantry. Searching the site of the Alabama Department of Archives and History I find one listing for a man named N.P. Whisenhunt in the Monroe County Militia (Home Guards). It would appear that he was otherwise exempt from Confederate service:

http://www.archives.state.al.us/civilwar/soldier.cfm?id=217066

What is your source for service in the 37th?