Glad to hear she hasn't got any pain tonight.
It takes a while to work out what the triggers/signs are. It might help to keep a brief diary of what she eats and anything significant like being overtired, upset or stressed about anything.
With ds, he starts to look pale and tired, then goes a funny green colour in a wide stripe down the centre of his face (I've never seen anything quite like it to be honest). There's often lots of yawning, and he seems to screw up his eyes a lot - he's also abnormally quiet. If it gets that far, he then tends to lose his appetite and just wants to go to bed.
The signs would probably be completely different for your dd though.
Keeping a diary did help us to identify the triggers, although to be fair, we were keeping a diary for other reasons and noticed the patterns emerging.
Good luck with the GP and eye test. You never know, it could be something as simple as eye-strain, in which case you could have it all sorted by this time next week.
I'll keep my fingers crossed for you.