I feel pressure feeling in my head and eyes when laying down and occasionally when standing up, my eyes get a large floaters when this happens, why?

Positional headache: Typically, intracranial hypotension causes a postural or positional headache. Headaches with a positional component it is always a red flag and need to be evaluated to exclude a lesion in the posterior fossa or a condition with low CSF pressure. Rec.: see an orofacial pain or headache specialist for further investigation and management.

Floaters..moving: Pressure feeling .... can be due to many things. I will comment on floaters. Changes in the gel which occupies the center of the eye can cause floaters in the vitreous. Most of the time they are benign. The degree of vitreous liquefaction affects mobility of the floater with movement. Sometimes, they are associated with retinal tears and can cause detachment. Get a dilated eye exam.