A choroidal nevus that was definitely NOT there two years ago, and now is so large that supervisor's are being called in, is concerning. Now its possible that it WAS there 2 years ago and not noticed by whomever examined the eye, if your eye was NOT dilated 2 years ago it generally is impossible to check the peripheral retina for choroidal nevus. Choroidal nevus are like moles on the skin. If they are small, flat, have uniform pigmentation and smooth borders not likely to be a melanoma. HOWEVER, that being said you need to see an Eye MD ophthalmologist, if the people that saw you were ophthalmologists and they were concerned you need referred to an Eye MD retina specialist.