She's 4. I'm assuming coming 5 this year?
I'm going to warn you - 5 and 6 are pretty awful. Keep pushing, keep riding, give her lots of brain breaks. This is totally normal.
It's good to find things that keep her mind engaged (trail rides, etc) and her body worked. You might also want to set up trail/bombproofing courses. Try side passing over scary objects, backing through poles, having tarps, pool noodles going through a hanging bead screen, etc.. etc..
It does get better, in a few years. Lol.
Have fun and good luck!
They say money doesn't buy happiness -- well happiness doesn't buy horses!