Start by contacting your daughter's guidance counselor. They will know which scholarships to pursue/investigate/explore.
If she is interested in the medical field, particularly going to medical school, as of now she doesn't really need to worry about her ACT score unless it is unusually low (a 21 is not unusually low). What she will want to focus on, however, is majoring in something like biology, chemistry, or pre-med, and really, really hit the books hard in college so she can get good grades and begin to build a solid academic resume that would look attractive to potential med schools.