Can Taking Amoxicillan Be Safe For Ear Infection?

My 12 month old has an ear infection and started taking Amoxicillan. As soon as she started on it, she got a mild case of diarrhea which i know is common, but everytime she goes in her diaper she starts screaming in pain and she breaks out in a rash. I change her as fast as I can and apply Desitin and she screams like she is in terrible pain the whole time. The rash clears up fast but the next time she goes in her diaper the rash comes back before i even have a chance to change her. Is this an allergic reaction to the medicine? Should i stop giving it to her? It is late at night and i cant call her dr. right now