its called anxiety, heart starts beating more rapidly,paronia felling, it happens to alot of people when there really high, what happen to you was anxiety that you made even worse by thinking it was laced and the im gonna die feeling:stoned: espically when your alone,this happens to alot of begginer smokers and it happened to me back in the day when i started, and you'll proabobally swear it was laced by the way you felt but it was just being alone in your room really high and paronia running threw your bloodsystem making you fell like you just smoke some crack or some shit like that,thats the only inperfect thing about marijuana that you will usally get anxiety if you smoke too much and if someone said if they didn't ever they would be lying