About 15-30mins after I brush my teeth & use mouth wash, I get for a lack of a better term a type of film in my mouth. What causes it?

Probably alcohol. Many mouth washes have alcohol in them that can dry out the mucus membrane of the mouth giving the feel of a film. Try a mouth wash without alcohol.
Might be. A protective film from either your toothpaste very common and beneficial with colgate "total" or from ur mouthwash.
Either. Some types of oral rinse has caustic or highly invasive substance to improve its effects. Also some toothpastes has abrasives that might cause that film . Consider replacing either or both toothpaste and mouth rinses and remember to brush your tongue as well.