Itu memang boleh jadi side effect, tau, some of my mum friends yang makan Duphaston also complained about tummy issues first few days, your body is adjusting to the hormones lah. But cirit birit yang teruk or terus-terusan, better check with your doctor or gynae, ok, because they need to make sure everything is fine and maybe adjust the dose or timing of meds you. Take care!