It's the 8th day our 3 year old child has been using Omnicef (after a 10-day amoxicilin that didn't work), and it's been only getting worse and worse. No you're not crazy, she is complaining about leg pain. She is constantly crying and she usually never cries or even whines. So this must be definitely a side-effect of this drug. We will cut this drug off today (will not complete 10 days) and will tell our doctor about all this. However, they usually don't take complaints seriously when we mention we read it on the Internet. On the contrary, we're getting real complaints from real people with real pain.