Yes you can put weed in hookas. I imagine you can be allergic to weed just about anything, weed is a plant, lots of people are allergic to different plants, I would say more than likely an allergy to cannabis is very possible. I'm not a doctor though, so I don't know for sure. The fact that you had your eyes closed and you were tripping out the second time indicates you were pretty dissociated and knowing that it could have easily just been simple nausea. The only thing that bugs me about it, is you said you never throw up when drinking. Not sure, everything effects everyone in different ways, I stick by the lower dosage, and possibly an additional anti-nausea drug near by.