I Get A Very Oily Feeling Coating On The Roof

I get a very oily feeling coating on the roof of my mouth on a regular basis. Sometimes I think it is connected to having animal fat - like cream or butter. However, it also just happens sometimes. This morning I woke with it and it hasn't gone away some hours later. I also feel extremely tired, with sore eyes, a very blocked left nostril, and just generally feeling like I've been hit by a bus. I recently finished a course of antibiotics for a bad throat infection.