I have severe floor dropping sensation. diangosis bppv but nostagmus not evident anymore. lying down improves it. what could it be?

BPPV: If bppv is mild, nystagmus may not be evident. The "floor dropping sensation" you describe may be due to other causes, such a orthostatic hypotension, which is a transient drop in one's blood pressure upon getting up from a lying or sitting position. Lying down would alleviate the sensation.

POTS: Postural orthostatic tachycardia syndrome (pots) could explain symptoms of "falling out" improved by lying down. In a fortyish male i would expect to also see a severe chronic pain syndrome from a previous mechanical injury to a limb or the spine. A neurologist might be the best specialist to diagnose.