and she might have picked up on that. i would try harder to project confidence next time.
it might be that it is a self-feeding cycle – when you don’t “let the tantrum be”, and rather become distressed yourself, it is causing the tantrum to grow larger, because your child can see your distress.
if you see the tantrum coming on, you can carefully lead your child away from anything that might be behind her, so that she does not knock her head on anything as she falls down. be calm but ready to place your hand behind her head if she throws herself backwards (stopping her from hitting the floor hard), 