1. Check that the knobs on the stove are completely in the shut off position.
2. Have you cleaned out the gray and black tank THOROUGHLY?
If not fill both of the tanks up and add a couple of bottles of lemon cleaner. Let it sit overnight. Drain each tank 'separately' and fill up again with cleaner and dump. AND watch what color the water is coming out. if not running clear repeat process for the tank that is not running clear.
Don't use bleach until you are 'sure' the black tank is empty. If there are chems still in the tank adding bleach will create deadly fumes. After its running clear then you can do a fill tank adding bleach to it that will take care of any remaining odors.
since you have health problems it would be best to fill and drain a few more times to remove the smell of the bleach.
Pick up one of these so you can see what is coming out that way you will know if the tanks are the problem.
My guess is the previous owner left you with some nasty dirty tanks. Or it sat while it was for sale without the tanks being completely dumped.
If you don't have a hook up at home find a local CG and stay the night and do the cleaning process while you are parked hooked up to a sewer hook up.
It's what I had to do with my first used MH.
We must be willing to get rid of the life we've planned,
so as to have the life that is waiting for us.