it started when i was in my teens, back in the 90s, and i'm pretty sure it was caused by immune reactions to vaccines given to babies
yes, i was already starting to become an antivaxer before i finished school, it was after i figured out that the two hep shots i got 1998 and 2006 precipitated psych problems that i was like, yeah, nah
and after 2020, they upgraded the SIDS to SADS which is where adults "suddenly die" - usually of cardiac conditions, but it is at base an immunological problem related to blood coagulation