How Can Scalp Itching With Hair Fall Be Treated?

I had botox injections in my scalp for migraines. About two-three weeks later my scalp was itchy. so itchy that i had people check my hair for lice. I would go in the shower and just scrub my head because it felt good to scratch it. Then about three weeks later i noticed some hair falling out. It has gotten gradually worse. I am down to about 1/3 of my hair. Everyone says it can t be from the botox, but nothing else had changed. same shampoos, no new meds, no stress in my life. Could it be from the botox and what can i do to stop it?