Question about kidney infection?

I went to the ER this past Sunday AM with horrible pains in my stomach and not being able to urinate. They gave me a catheter, some saline, and pain meds and sent me on my way hours later diagnosing me with a bad kidney infection. Yesterday the stomach pains were gone but today they are back almost as bad as they were when I went into the ER. Should I go back in or is this normal? I have been taking my antibiotics and resting, but I had to come back to work today.