11 week old had 2 month shot. Doc said give tylenol (acetaminophen) for pain and fever. Can I give her infant motrin also. Since I have some all ready have some.

Motrin vs Tylenol (acetaminophen)? No, Motrin (ibuprofen) is contraindicated for infants under 6 months of age. Stick with Acetaminophen (tylenol).
NO. Ibuprofen is not approved for infants under 6 months. Their kidneys are not mature enough and it can cause significant damage. You may not have to give your child anything for her shots. The option to wait and see is always open.