Hi, Canadianmom . . . I have a home prescription reference, so I looked up Clindamycin. Generally rash and digestive problems (nausea, diarrhea, etc.) are side effects of this.
I got the inspiration to look up Lidocaine (most commonly used anesthetic by dentists) and found that mouth, throat and tongue swelling is a side effect. You should contact the dentist as soon as possible to make sure what anesthetic she was given and what to do or expect if it was this.
Best of luck! I hope the bumps go away soon.