After Hurricane Sandy many displaced folks were setup in RVs by FEMA. Many of those folks complained about the RVs making them sick.
It seems the out gassing of the products (glues, plastics and treated woods..etc.) used to construct the RVs was causing some folks problems. FEMA suggested the people leave windows and vents opened as much as possible and use air filtration devices.
First I would clean everything in the RV with a good cleaner or have it professionally cleaned. Then if possible I would try to leave the RV opened up for a couple of weeks. See if it still makes you sick. If it does get a heavy duty air filtration device and run it constantly.
You may need to sell it to get your health back.