Hello and thank you for choosing HCM for your questions!
I read your question and found it very relevant since young babies are always getting into trouble and this is one of those cases.
I think that you do not need to be panicked about your baby's health at this point.
Advil is
ibuprofen, a medicament we usually give to babies when they have
fever, sometimes alternating with
paracetamol.
Ibuprofen can be given for your baby, but at low doses. However, even if she has swallowed one Advil tablet (200 mg), there should be no problem. If the size of the tablet is 400 mg, then the body temperature of your baby could be lowered too much and if this is verified then you need to warm her up, for example by having showers with warm or hot water.
In any case, you should carefully monitor her body temperature for about the next 4-6 hours and act accordingly.
I think that she will be fine.
Thank you and good luck!