I have well water since using it (7yrs) we have noticed cavities starting and even had our teeth breaking! Could it be th water? Could it cause headach

Well Water. Your private water source almost certainly does not contain fluoride, which in very low concentrations has been shown to prevent cavities and strengthen teeth. Fluoride supplements? Fluoride containing toothpaste or rinses? Regular dental check-ups and cleanings? You may want to have the water tested just to see exactly what is in it.