I was thinking the same thing^ that's a pretty low dose. At 150mgs I feel like the coming up of an MDMA high but it lasts like 2-3 hours maybe then I'm tired. Never felt any effects from a lower dose.
Seeing as how OP is fine and has a healthy distaste for DXM while now understanding their relative sensitivity to it and probable mechanism behind it, I believe this thread has run its course.
Feel free to send me a private message in need be.