Can Botox cause diarrhea and anxiety or am I just sick and neurotic?

It is very unlikely that the Botox has anything to do with anxiety and diarrhea. Don't worry. If you are not feeling better in a week or so I would call your primary physician or whoever it was that prescribed you your antibiotic. Chances are this is just an unfortunate coincidence.

Don't worry, Botox is not the cause of your symptoms.  It is most likely coincidental.  When Botox is administered it stays where it is injected.  It does not cause systemic effects.  In fact, Botox is metabolized locally where it is injected.  After the injection, Botox is absorbed into the surrounding cells and you will see the effect within 3 to 5 days.  Good Luck