spam text sent from "me" but it obviously wasn't. how do i block it?

i know that most spam texts are sent from spoofed numbers, but i block them anyway. but recently i received a spam text (with a malicious link) that shows in Messages as being sent *from* me to me.

tapping info just brings up my contact information. there is nothing in the app that provides any info about the source of the text - it doesn't even tell me if the text came from a phone number or email.

i'm monitoring my icloud and mobile accounts for any sign they may be compromised, but it doesn't seem like it so far. but is there any way to figure out where this spam is actually coming from, or how to block it?