Yes, PF is certainly an excruciatingly painful condition.
I think if you read through a lot of previous posts you will get an idea of what to try. And when I say try, it is just that, what works for one person may not help another.
Cushioning heel pads are a must, and a supportive soft but not bendy shoe is good, people use Birkenstock sandals, Crocs, trainers, etc.
Rolling on a frozen water bottle can help but also hurts, taping can be good, ibuprofen gel, toe stretching all can help.
I find complete rest for several days is the only thing but of course for many people this is not possible.
The knee pain could be the result of walking in a different way to offset the pf pain, this can happen quite quickly and also spread to the hips.
PF as I've said before is a non life threatening condition and so doesn't get the interest or funding to really study it. The result is very much trial and error by the medics with no firm diagnosis of the actual problem, and if one thing doesn't work then just try a string of others.
Sorry if all this sounds rather negative but it is just what I have found, but i hope your daughter finds some relief soon. When it has cleared, calf-stretching is a must as this can prevent a further bout - well it does seem to work for me as apart from the odd twinge I have been pf free for over 18 months now.