It is now 2am and my 22 mo old has been on omnicef for pneumonia for 2.5 days...starting the night he took it he started waking up in the middle of the night just screaming - he does not get night terrors, this all started happening the exact night he started the medicine...he did it the next day when waking up from a nap as well and then again tonight. My husband is with him and I am searching the internet on this stuff - I have no doubt it's the medicine after reading these similar stories - and will be calling his DR in the morning. He has also had 8 runny diapers in the last 15 hours since starting it.