Like 1000 factors that can cause. Your question doesn't make sense. see an otolaryngologist. Tonsillitis, rotten tooth, type of food, poor hygiene, etc. The genital part is normal if you don't clean it well, if you masturbate frequently or if you lubricate constantly in each casual erection.
Well im guessing that you are breathing in this gas and it stays in your body. One way is by swallowing toothpaste but i dilute it a little but the problem is that the breath comes back and it makes a very strong patm reaction so i think you have to get rid of what’s causing the bad breath first then you can use the toothpaste