Mayerdale, I haven't been on this site in so long... I've forgotten how to use it. Let me know if you get this message. Regarding the fish smell...it's so strange...it suddenly stopped. Just like that. Coincidentally, the house behind began a massive extension project (still ongoing) requiring excavation of montrous proportions. They are about 100 feet from our house. Someone (not sure it was on this site) had told me that our problem seemed to him to be one originating from the ground and that maybe a neighbouring property was responsable. It didn't seem possible at the time but I don't know...maybe it was. Was is around your own house...other old houses? Could their septic system be draining into your property? Tell me more...I feel for you. It's awful isn't it?