For starters, Bob isn't here but we'll try to get you through this.
Anyways, have you contacted your personal physician? If your Health and Welfare 'folks' say the gasses are extremely harmful and combustable, then they should be able to tell you what they're 'referred to' as. For example, if they say you're being exposed to Sewer Gasses, that's what you tell your physician. The more specific the H & W folks are, the better treatment you should expect from your physician.
Since you are saying that you're getting your problem fixed, I dont' think (at this time) you need to go to plbg.com to get more info. The Health & Welfare folks should be able to tell you what's up. Also, consider having your tank and such inspected by your local municipal government's inspector. Perhaps he, since he will be on-site (and not on a Forum, here or otherwise), can tell you more about the gasses too. With all this 'new' info, you should be able to talk to your physician.
Other than that, I don't know what else to say other than 'fix' the symptoms too. My best to ya and hope this helps.