What would cause a dark spot in my center of vision while turning head quickly? i've had a new onset of floaters a month ago. right eye muscle strain, and my eyes are now struggling to focus on objects. i have possible intercranial hypertension?

On occasion, pseudotumor cerebri can cause visual obscuration episodes and this may correlate with your situation. But it would be of great value to seek ophthalmological consultation if this has not already been done.

You need to have a work up for intracranial hypertension. This is certainly one of the things that can cause your symptoms. Vitreous floaters are what you are describing, this is a change in the fluid, vitreous , in the back part of your eye. Your need a detailed/ complete eye exam!