Wa'alaikumassalam! Aih, I get that too sometimes, masa batuk teruk memang perut sakit, especially if you're tensing hard lah. A few of us mums noticed it happens bila batuk berpanjangan or tarik nafas dalam-dalam, sebab tekanan pada abdominal muscles. Could be angin, could be just the strain from coughing, tapi kalau it's persistent or really painful, better check with your doctor to rule out anything else, okay? Hope it passes soon!