These kinds of headaches are horrible. Years ago when I first started having them, DH said he wouldn't let a little thing like a headache stop him. I told him I hoped he never had to experience one, if he did he'd understand. It wasn't long afterward that he started getting cluster migraines. Granted, I've been told they are even worse and once the cycle begins it is hard to stop. But, they weren't such a little thing anymore once he experienced them.
I too take propanolol and haven't had one in a long long time. I feel for your daughter, hope she feels better soon.