Comedown with 3MMC? Experiences? Which substances give you the worst comedowns?

Hey, my bf has done 3MMC once and he told me that it gave him the worst comedown of his life: he couldn't sleep at all for 1 week, wanted to kill himself, etc. The thing is that his mixed 3MMC with another stuff (he doesn't remember what), maybe MDMA? We don't know. Therefore, I was wondering if you have also had terrible comedowns with 3MMC and if there's a way to avoid them, cause when I've done it before, I've felt it very smoothly, with 0 comedowns. Thanks!