I forgot to tell my Dr I was breastfeeding my 3 month old baby and got 25 units of botox. Should I stop breastfeeding for good?

I certainly don't know for certain, but it's hard to imagine how Botox could end up in breast milk.  Even if it did, Botox is a protein that would be denatured by the acid in the baby's stomach.  I would probably avoid injections of botox in breast feeding women because of the legal sharks swimming around, but I think that you have nothing to worry about.

Hi Suze.  If you want to continue using Botox, we would recommend that you stop breastfeeding (or vice versa).  While there have been no studies to suggest that using Botox while breastfeeding would harm you baby, there are also no studies that show it's completely safe.  

At our practice, we do not allow it for liability reasons.

There are no studies on the safety of Botox during nursing and I would not expect one to be performed anytime soon.  In my opinion, it is unlikely that any problems would arise since the first person to run into systemic toxicity would be the mother but it doesn't seem worth the risk to take any chance at all.  I would hold off for now.