Does Taking Omnicef Cause Pain In Calves?

Hi My 10yr old daughter, on antibiotic Omnicef generic version, she had a fever of 99.-101.9 on and off for 2 days, called doc, they seemed to think symptoms of strep and called in the Omnicef. After taking the 3rd dose of this med. she started having pain in both calves, now walking on her tip toes because she can't put pressure on both feet to walk normally, she says no pain when laying down unless she stretched her toes toward her knees. Is this a medicine side effect? She's also been on liquid Advil alternating Liquid Tylenol to help with pain. She has no fever now at all, just has congestion with a slight cough. Should we be going to doctor now? The offices are so full of flu, viruses and strep, we hate to expose her.