I've been seeing this purplish green circle in my right eye (my right), it always appears at the same place and it only shows whenever i move my head. i've also been seeing a small green cloud in the same eye whenever i focus my vision on something?

It's hard to tell you what's going on without more information. However, most likely, this is a posterior vitreous separation (PVD) and what you're seeing are clumps of protein from the vitreous gel. Sometimes they can appear as a "Weiss ring". The concern is that there is an associated retinal detachment and you will need a dilated retinal exam with an ophthalmologist to rule that out.