11 week old pullet acting strange

Hello! First time chicken owner. One of my pullets is acting odd. She’s a naked neck and normally one of the more skittish of my crew. Yesterday, i noticed that she was drawn into herself and a little puffed up. I didn’t notice anything blocking her vent. She’s not running around like she normally does.

I was thinking she was constipated last night because i noticed her almost straining, but then she pooped.

I’m really worried about her and wanted to see if anyone has seen something like this? Any recs? I’m going to find a vet who can take a look, but thought I’d also ask here while i call around.