Omnicef and acts

My 24 month old daughter was prescribed Omnicef for a sinus infection. She began waking up multiple times in the night screaming. She acts like she is in pain, but won't tell you what hurts. She freaks out when you touch her when she wakes up like that. She also appears to be hallucinating and we're not really sure she is even waking up. She has had 4 doses and now the mood changes have gone into the day hours. We have contacted the doctor and they agree with us that she should stop taking the medication. We cannot confirm the bowel movement side effects because she has not had one in 2 days. We checked the side effects insert from Omnicef last night when things were bad and nothing was on it about nightmares. I understand that not all children react the same to medications, but there are too many with the same reactions to overlook this.