Hi there,
I've been experiencing this since last October (8 months ago), and I've recently been reading this forum. It has been greatly consoling to know that people share in this experience. First I'll quickly outline my thoughts, and second I'll pose my solution.
I share in the experience of people around me at worst coughing, but often sniffing, sneezing, scratching, or giving weird looks. This generated depression and social anxiety in me. It all started after I (in an uninformed way) messed with my breathing. I had a few instances of strange and amazing results with people around me acting euphoric and being able to indicate exactly what stage my breath was at. This led into a downward spiral of "off" or "un-natural" breathing which I believe has influenced my magnetic field or aura in a way that often makes people feel uncomfortable, leading to coughing and the rest of it. By deviating from nature, nature is sending signals back. Coping is very hard, as well as finding answers through this forum, but all the people here seem to be coming from a good place (save for those trying to sell products).
Firstly, I am on the side of believing that this has not to do with smell, odour, or gas. I understand that there are conditions out there that cause odour such as fish, garbage, or worse, and I'm confident this is not that.
Secondly, I do think that diet and exercise are always amazing and underrated, but I do not think that is the ultimate solution.
Today, although requiring a fair bit of effort and awareness, I was able to have a very close to normal day, and I've just started breath re-training. It's as if I'm working towards breathing at a slow and natural way into my pelvis, with little to no visible movement from my chest or abdomen. This web-page is my go-to breathing retraining resource.
http://www.rbphd.com/Docs/breathingretraining.htm
Also I have started doing 16 hr a day fasts, and going for a run every day. With all these combined along with beginning some yoga classes, (and quitting weed), I'm confident that I will be able to fully cure this in the same way that it started, by fixing my breathing.
Good luck, please let me know if this works for you