Welcome, @elliesugar. This must be distressing for your daughter.

According to this article:
- Can Crohn's Disease Cause Hair Loss? - Healthline: https://www.healthline.com/health/does-crohns-disease-cause-hair-loss
"People with severe Crohn's disease often experience symptoms outside their GI tract, too, like inflammation in the joints and skin. Hair loss increasingly appears to be one of these symptoms. In fact, a 2021 research review suggests a connection between IBD and alopecia, which is a type of hair loss."

I moved your question about Crohn's and alopecia to this discussion that @sandyjr started about her daugher that also includes helpful posts from @eden:
- Crohn’s disease treatment and hair loss: https://connect.mayoclinic.org/discussion/has-anyone-had-hair-loss-due-to-crohns-diseasetreatment/

May I ask how old your daughter is, Ellie? Might you be looking for a second opinion at Mayo Clinic?