Wa'alaikumassalam! Alhamdulillah HB okay dulu, memang BP turun adalah normal dalam pregnancy, especially kalau you're in your second or third trimester, tapi turun 11 points naik-naik macam tu memang boleh bikin dizzy dan scary lah. A few of my mum friends experienced something similar and most of the time it's dehydration, kurang tidur, or you're just moving too fast, tapi sebab ni first time untuk you, best la you follow up dengan doctor, bukan just nurse advice je, to rule out anything yang needs closer monitoring. Minum air memang penting, tapi kalau you terus rasa giddy, blur, or shortness of breath, jangan tahan, terus call clinic or go to hospital, okay? Take it easy for now and try to rest more. Hope your BP stabilise soon!