What is their feed?And she Bobby’s her head and so does the rooster occasionally and they both look slightly unsteady when they walk
That's not egg binding.
It could be genetic, daylight related, or nutritional.
Since the rooster is also doing a head bob thing and kinda wobbly.. I would suspect nutritional OR possibly even disease related since it sounds like mild neurological symptoms.
You mention fleas, which chickens don't usually get. But there are several other mites and lice that could cause irritation including a head shaking of sorts and since they suck blood, under heavy load it could cause anemia and weakness. Your boy's comb has nice red color so it doesn't indicate parasites as THE issue, but have you seen anything on them? Can you check your rooster below his vent and on his abdomen after dark using a flashlight and parting the feathers all the way to the skin. That's when it's easiest to see crawlie things running away.
Any sneezing, watery or bubbly eyes, and crusty nostrils?
Lets talk about feed for real.. it *can* make a huge difference in ALL things immune system related including parasite control and laying.
Are you able to get a video of the head bobbing or unsteady walk and post a link here?
Do they have a larger flock or is it just the two of them? What is their age?
I'm just looking for clues for consideration so please don't panic at things I mention.