Hi, thank you for posting. Smoking causes the recession of organism immunity. The organism is easily affected by viruses, bacterial and fungal infections. If you live in North America, you have frequently stuffy nostril and then you have to breathe by mouth. Faint can be caused by dropping glycemic level, or by nicotine poisoning, so you should quit smoking . I think you suffer from fungal infection (Oral candidiasis). You need to check glycemic leve(on an empty stomach) to eliminate the risk of Diabetes mellitus. You need oral culture test. You also should contact an Otolaryngologist to check your nose.