A fecal float would determine worms as well.I agree, EEs don’t start laying until about 30 weeks, my comment about her being eggbound is wrong, I didn’t check the breed (or look at the photos lol) I think if it where lice or mites that more than one bird would be acting up, but it’s good to look. The fecal float would be good- not everyone’s favorite thing but it could help you determine what the problem is. Could it be worms?
Lice/mites can be on just one bird if it's sick, always best to check.