Based on the latest string of attacks, my bet is it's Daesh/ISIS (or a couple of their fanboys).
For those who don't know, Daesh has been suicide bombing the fuck out of Muslims this week, even in holy city #2 Medina. Suspicions are that this is desperation behavior as their loss of major territory very soon is now inevitable.
https://en.wikipedia.org/wiki/List_of_terrorist_incidents,_July%E2%80%93December_2016