Leeneia,
Yep, I use a flat pick..but I don't anchor my pinky. My right forearm gets crampy if I try that.


All three of us here have the symptoms in our left arm, so in this case, it probably doesn't have much to do with our picks. Of the three, one always uses a strap..one sometimes does..and I never do.
One has played longer than me and one started fairly recently.