I agree with everyone else in that you should definitely seek professional help, but that being said I do have some tips that helped me that might help you and your daughter as well.
When she asks something along the lines of “Is there glass in my foot?” Don’t just say “No, there’s not.” Instead ask her why she would think there is glass in her foot. If she says it’s because there was glass there before, calmly tell her that all the glass has been cleaned up. If she’s still worried then tell her that you are keeping a look out for glass on the sidewalk (while still assuring her that there’s none there at the moment) and that you promise you won’t let her step on any. Also remind her that she would be able to see any glass before stepping on it as long as she watches her step.
I also completely understand her fear of splinters as that was also one of my ultimate irrational fears as a kid. I am very splinter prone when it comes to handling wood. Mostly because I hold everything with an absolute death grip while simultaneously sliding and shifting my hands constantly. This is because of the tension and discomfort that comes with holding things. I don’t know if this is her exact experience, but ultimately I can only recommend wearing garden gloves when around unpolished wood.
I hope this helps, but I know that everyone’s experience with cp is different so all I can really say is good luck to the both of you.