Hitting and Headbanging

My 17 y.o daughter, Chloe, is constantly hitting and headbanging her head. 

It used to be every Wednesday sometimes Thursdays too, which are both the days she sees YOT. This was only a couple of meltdowns which showed these behaviours. 

Over the past couple of days, school have been phoning me worried and confused because she is now hitting and headbanging all day everyday, including when she is not having a meltdown. 

When this behaviour occurs, staff have taught Chloe to hold their hands therefore it's easier to direct. Also squeezing hands every time she wants to hurt herself. According to staff, Chloe is now frequently placing her staffs hands on her head, for deep pressure I believe. 

I believe the reason for the behaviours are: deep pressure on her hand and hands, frustration because to me it seems like she cannot regulate herself fully. Over the past few weeks, her outbursts have been more 'challenging', angry, aggressive and a lot stronger for her and everyone else. I will also say it is taking a lot longer, over the past few weeks, to calm her down, most being around 10 hours for her to fully regulate. 

Staff are no longer restraining her because it makes the situation worse which is worrying for me regarding the injuries she may get. Since they've stopped she has started to become aggressive towards staff as well. 

Im not too sure on a solution for this, if it is sensory seeking for deep pressure and being unable to fully regulate. If anyone has any tips for myself or the school to help Chloe, it is greatly appreciated. 

Thanks in advance, 

Lucy