A shadow now floats around in my field of vision. is it retinal detachment or tear?

Need an exam: This cannot be determined without an eye examination, which should be performed asap!

Unsure: It sounds as if you have had a posterior vitreous detachment. This is a situation where the vitreous(jelly) of the eye detaches (not a retinal detachment), it then "crumples" up leaving dots, spots, strands of blurry vitreous; i.e. The "floater". You should have an exam to ensure the incident did not tear the retina, which could lead to a retinal detachment.