You might be living in a toxic house!! There may be a lot of mold in it, even if it is new house. You might have it tested for black mold or other mold spores. These molds are very harmful and make people sensitive like your whole family!! It is not in your mind!! Did you get new carpet or has anything changed just before these symptoms came on. Retrace what might have happened. Did you just move into this home. Maybe the ducts need to be cleaned. Do you have a leaky roof or plumbing. Do you have a wet basement. These are some clues. Look into mold remediation if this is the case. Your home may very well be sick, especially if you all have sinus or breathing, pulmonary problems. Hope this helps!!