Cramping at 21 weeks

Chloe

I am currently 21 weeekks today. For past 2-3 days ive had very mild constant cramping feelings. Its not servere and no bleeding. But as its niggling away its really irritating because i can feel it. Its there constantly and eaases for a while then comes back. Does anyone else have this problem. I saw the doctor today and urine seems fine but been put on antibiotics as a precaution.