Kundalini syndrome. Not great. Widely written about but you need to know where to look. Gopi Krishna is probably the most widely known case, but you only have to peruse Reddit's Kundalini subs for more.

That's my issue with all this mindfulness stuff. A load of Westerners ripped the guts out of practices to shed the "dogma". But that "religion" they chucked out was the result of generations of people interpreting these strange experiences and is supposed to provide some kind of map of the terrain. Only since not everyone experiences spontaneous Kundalini events most of them don't understand the symbology.

I'm told a guide is invaluable, if you're fortunate enough to track down someone legit.