How frequently is she doing this motion, and does she seem distressed by it? Also, how old is she?
There are a few possibilities here. She could simply be adjusting her crop, which is normal. If she's a baby, she could be begging for a hand feeding. If she's and adult and she's doing it excessively, it could be a sign of a respiratory or GI infection. So we really need more information before we can advise you. A video of the behavior would be helpful too.
Sounds normal to me. I was alarmed at first too with what I thought was yawning, but I was told by those here who know a lot more than me, that it's adjusting of the crop that makes them do that. Moulting might cause the scratching. I know it makes them itchy.
She's 5 months old (about). She opens her mouth, stretches her head out and then back again and then repeat. She's not doing it constantly, just a habit we have noticed. Maybe 5 times a day? And maybe scratched herself 10 times or so?
That's normal, then. it's her way of adjusting her crop and clearing her airways. Scratching is also normal, unless she seems distressed or starts to develop noticeable irritation. The bald spot is probably genetic.
I agree, it all sounds normal. The bald spot could be genetic, but if you just got her and she was previously with other birds, it's possible that one of the other birds plucked her. If it's genetic she'll stay bald, but if it's plucking the feathers will grow back.