25(x)-NBOMe is an extremely common fake LSD lately. Specifically, 25i-NBOMe.
If your tongue goes numb there is a very good chance you have been given 25i. As trav mentioned sometimes blotter can be bitter... However IME it's only bitter, mild, and goes away. NBOMe will leave a taste in your mouth for at least an hour, at least mine did the time it happened to me.
Timeline wise it's very similar to the real deal. It can also be complexed and put on blotters the size of regular LSD as well... I believe DO(x) needs larger blotters (I may be wrong on that)
Heavy body load is another sign. Nausea on the come up is very apparent on 25i, and 25c produces an unexplained paranoia.
That's all the information I can provide and I hope you figure it out. Elrich reagent tests are available now that can detect the real deal.
Good luck!
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