Do you have a solid fuel stove? When did you last sweep your flue or check your burner? There were two bad fires on boats last winter - both boats completely burned out. The cause has not been specified BUT it does tend to be burners that cause fires on boats. If you haven't swept your flue this winter - do it now. Signs that your flue needs sweeping - no draw, smokey fire, glass gets dirty quickly, fire is more smelly than usual. If you burn mostly wood you should be sweeping every few weeks at the very least. Useful links below (please add any more useful links if you find them).
https://www.boatsafetyscheme.org/stay-safe/solid-fuel-stoves/
Also NEVER keep hot ash from the fire inside the boat - store it outside away from anything it can set alight and away from air vents in a metal bucket which has a lid. A friend suffered carbon monoxide poisoning from her ash bucket, another friend had a bad fire inside her boat caused by ash and another boat was completely burned out by a fire caused by hot ash setting items in the cratch alight.
"am feeling nauseous have no idea why and headachy" - how's your fire, flue and ash?
https://www.nhs.uk/conditions/carbon-monoxide-poisoning/