so i became a little worried after for playing about 2 years anchoring, my wrist became a little cramped if i alternate picked for 10 or more minutes straight (a common thing, my longest time was something like 42 minutes of nonstop speed picking.) well i started to not anchor, within a hour my picking while a little sloppy was getting back to normal (except not anchoring), well suddenly my wrist and forearm are sore. i am not sure though if it is because of my picking technique (i close my fist and sometimes when i pick my hand rests on the strings for about half a second.)
I would say you've done something funny with your posture and you haven't actually improved your control, so you're still just powering through the strings without noticing that they push back... take things a little slower.
Same thing with me. Ever since I read that sticky, my picking arm has become sore.