Have you completed the course? Some antibiotics do upset stomachs (I had to stop taking erythromycin for similar reasons). If you're still due to take more, I'd contact your GP to say you need a different one. If you've finished the course, I'd just mention it to your GP next time you go that you think you're sensitive to that antibiotic.
It's worth taking a probiotic to help regulate your gut again when taking antibiotics and now that you've stopped. It should settle down in a few days now you've stopped them.