I noticed some of Vincey's feathers underneath were missing and the skin looks red. I couldn't quite get to it but managed to get a photo below. Not sure if this is normal as it is underneath some of her feathers but it does look red?
Does anyone know what this could be?
She seems ok in herself and I havent really noticed her picking/plucking the area.
You need to have your budgie seen by an Avian Veterinarian for the proper diagnosis and treatment plan. If there are no Avian Vets near you, then an Exotic Pet Veterinarian that has experience treating small birds is your next best option.
From the pictures, it is impossible to tell what is going on with that particular area.
If the issue is not caused by over preening or mites, then the doctor may need to run tests to determine the cause of the problem.