Pepto-Bismol - My 3 yr old daughter drank half the bottle of pepto what should I have to worry about

Half a bottle of Pepto-Bismol is quite a lot. It might be better to take her to the doctor.

Overdose symptoms may include increased thirst, anxiety, muscle spasm, ringing in your ears, dizziness, confusion, severe headache, problems with speech or vision, severe stomach pain, or worsening diarrhea or vomiting.

https://www.drugs.com/mtm/pepto-bismol.html

I think she will be ok, but call poison control, they are really up on accidental ingestions and they can give you very good info. It does have a form of salcylate in it, which is an aspirin offshoot. Once you call poison control, they will call you back to check on her. She is in my Prayers.