Botox for Hyperhidrosis - Worked Just for 2 Weeks. Normal?

I had botox injected 3 weeks ago and at first it looked very promising. 2-3 days after injection sweating was minimal but it did not last long. Increased perspiration was clearly visible after 2 weeks and after 3 weeks sweating is so excessive as if i did not have any botox. I was full of hope and now I am devastated. Why it did not work? Should I do it once again? Thank you in advance for your advice. Maggie