It doesnt sound to me like it was laced.... it sounds like u smoked like 4 different kinds of weed, and when u do that, each weed has a different high, and if u smoke all four at once.... you get fucked the hell up...
Im assuming mabye u werent used to being so stoned, so u had a panic attack...
And why the fuck would the robotussin have anything to do with smoking chron? you were taking medical doses right? Or did u mean u tripped on dxm...