Pullet is stumbling backwards! Help!

[Creede]

This pullet is about 6-7 weeks old and 0.75 lbs. She is smaller than the others but has always been so. She is eating, drinking, and my wife has seen her poop. However, she has been caught stumbling backwards, toes curled upward into air. She struggles with the flock when free ranging. Her tendency is to catch up to the group peck around a bit, until she lays down. Then she might peck around some more laying, just look around or take ANOTHER nap. She was the last one into the coop last night by far. She slowly took shaky steps to the stairway. Then she needed to flap her wings up every small step (Whereas she used to, and the others, just take about two jumps with a couple flaps only). This took significantly longer than usual, and she almost fell off. Getting up to the top roost was a similar scenario. Her eyes are attentive, and she makes regular chicken noises for her age. This began only a few days ago, maybe last Friday. I haven't noticed any other signs or issues. She seems fine with a will to live, other than her posture being poor and shaky. She will lay over a little stiff legged too (like when they are taking a good sun bath), but I noticed her legs are not stiff when she walks. I came to give the girls treats and she tried to get up and come over, but then just felt it was too much effort and laid back down. No changes in diet or routine that I can think of. It has increased in temperature to the 90's lately. She doesn't show signs of panting or anything.

I have placed electrolytes in everyone's waterer a few days ago. She received 0.25ml of Nutri-drench last night and today at noon. We do not have a vet near, and I will treat her if possible.