The chick is hopping around on one leg, which is worrying me a bit since I've noticed that the good leg is now starting to bow inward. When it's not eating, drinking, or sleeping, it usually leans against the toy stuffed parrot that is in the brooder.
The bad leg is the same as ever - stuck in resting position. It has slightly more flexibility now (only when I check, as the chick doesn't use it) and the hock is not flaring up at all, so I'm being cautiously optimistic. I'm still not 100% sure if it's a slipped tendon.
Yesterday another chick suddenly had a slipped tendon in its left leg. I knew for sure that's what it was since I picked it up right away and did the trick where you stretch their leg behind them - the tendon snapped back into place so easily (I was really surprised). That chick uses the leg but it doesn't/can't straighten it out on its own (it tries to use the foot), so I did some more searching online and am trying a method where you duct tape around the hock to hold the tendon in place (found it here). To me it has a dual purpose - hold the tendon in place, and keep the hock from being rubbed.