What Are The Cold Sweats,nausea And Visual Distortion After Taking Robitussin?

I took 180 mg of robitussin for recreational use about 2 weeks ago and while robitussin as a recreational drug is nearly entirely safe in the dose i took I have been feeling bad effects the past two weeks. These include cold sweats, shivering, nausea, occasional visual distortion (colors are brighter) and confusion/bad memory. What could his be?