Feeling sick since first day RVing

So if you have a history of sensitivity to chemicals, I'll bet that is exactly what is troubling you. What have you added recently, if nothing, then I'll suggest its that bug cheap wood smell that is getting to you and your just nose blind to it now. I suspect mold Get a gallon of bleach and a tooth brush. Check around the windows, vents, under the sink and like I mentioned, the mattress. Wipe everything down with bleach water and if your cloth comes up black at any point, that is probably your culprit. Also you said "cool RV" so can I assume that you have air. That is another great place to check for mold and for problems. Good luck, if you lived nearby, I'd come help but I'm in Washington.