My Husband Has Been Experiencing The Smell Of Nicotine Or

My husband has been experiencing the smell of nicotine or "old cigarettes" at different times during the day for about a week. When he wakes up during the night, he smells nicotine. He has never been a smoker! He is not on any new medicine. Has stopped taking Nasonex, thinking that could have been the problem. He is diabetic, on Metformin 500mg TID. I appreciate any guidance you can give.