Newly diagnosed Daughter

Hi, my 7 year old Daughter was diagnosed ASD 2 weeks ago. l have a 10 year old daughter who isnt ASD and a 1 year old boy(too early to tell). I find it difficult sometimes to get my older daughter to understand why my 7 year old is the way she is. The constant melt downs, clothes changes through her having toilet accidents, biting and chewing... The list goes on... Exhausting but I wouldn't change her for the world. we have really been left in limbo at the moment as we have the diagnosis but thats it no information and no support. Any gems of wisdom would be greatly appreciated.