BBT spike?

Ashley • stepmom to 9yo and 5yo; baby #3 born 02/04

I haven’t had a positive OPK yet (but I typically surge quickly) but had this huge spike this AM. Haven’t had one that big before that wasn’t tied to ovulation.

I know I need to have at least 3 to confirm o but, while I wait, any ideas of what else this could mean?