I have a terrible smell in my half bath-it seems to smell very organic with a tinge of metal -it started 3 weeks ago. We just had the floor replaced (in July) and the bathroom painted (August). When we tore up the flooring in the kitchen adjacent to the bathroom we found leakage. Come to find out the sink in the half bath had been leaking under the sink and draining out into the kitchen. We had the sink repaired. My husband changed out the toilet and seal as it was leaking, but the smell remains. When I open the window to the bathroom the smell disappears, but then returns when the window is closed. We do not have a basement, only a crawl space. Could this be mold in the walls or something large has died in the wall space. My husband refuses to have someone tear into the walls. Please help me- I am at my wits end.

Brfore a repair can be started you must first ascertain where the smell's the strongest. Look down the drain at all the traps. If they're full of water then you should be OK, but if there's almost no water in any of the traps then you could have a vent that's blocked. Also you've tried everything else you might want to consider replacing the wax rings in your toilets. Sewer gas can escape a defective ring yet not leak water when flushed. The wax ring can emit sewer gases from the base of your toilets and you will swear it's coming from the shower/tub drain, lavatory drain etc.
Sewer gases have a way of dulling the olfactory nerve and make detection nasally impossible.
You must realize that smells and weird noises are the hardest to track down when you're on site and just about impossible when you're not.
All we can do is point out likely spots. Good luck, Tom