I feel for you, too.
It's heartbreaking anytime anyone close to us has a health condition and is relying on us for care and for support.
I'm not really sure what PCS is, though I did Google it. Might I suggest, and this is solely from the top of my head: Contact your local chapter of MDA (March of Dimes), Salvation Army, as well as her pediatric (sp?) doctor/s. They will likely be able to offer you ideas on how to get support.
Also, a local chapter of PCS national organizations or associations should also be able to help in terms of where to find support, and, possibly, too, a respite grant or scholarship.
Please update, and soon.
".... This world wasn't built for people in wheelchairs ...."