Mosquito bites can lead to fowl pox which is a nasty disease and far worse than mosquito bites. There is a pox vaccine you can buy to vaccinate your flock against pox, not mosquitoes.
All the symptoms you describe point to another egg stuck. Chances are it's shell-less. Give her calcium citrate with D3 as in the photo below. Pop it whole directly into her beak and then place her in a crate on several towels to absorb her watery discharge. Make water with a little sugar in it...