How long do the side effects of "fake weed" last?

I tried this stuff called "southern max" last night which is a synthetic weed (like k2). Anyway this is the first time I ever tried this stuff, but I have smoked real weed many times in the past. I had a horrible trip, and I have never had any bad trips in the past. I felt like I was in purgatory, and I feel like I am dead or in a dream as I am typing this. I will go on to say I will never try this stuff again because what it did to me. I was wondering if this has happened to anyone before and will this "dreamlike feeling" last forever ?:(