Toddler had an infection in her stomach she was put on antibiotics for 10 days after i stoped the antibiotic the fever has come back , ?

Go back to doctor: Or seek a second opinion. A pediatrician would be a good source for information and advice if your toddler has not seen one yet. Cannot imagine what type of "stomach infection" is being treated.

Needs re-evaluation: If the cause of stomach infection was a virus, antibiotics wouldn't be effective. However, any viral infection may predispose to a bacterial infection. Thus after recovering from the viral illness child might acquire a bacterial infection, associated with fever, like an ear infection, for example, and in that case antibiotic treatment would be necessary. And re-evaluation is guaranteed.