Alamak, jangan worry sangat, a few of us rasa macam tu jugak dalam first trimester, especially kalau morning sickness teruk! Berat turun 5kg dalam 9 minggu mmg boleh happen kalau really tak boleh nak makan, tapi sebab you mentioned alahan truck parah, better check with your doctor just to make sure everything okay dan baby getting enough nutrients. Once morning sickness settle (usually around 12-14 weeks), weight biasanya stable balik, then baru naik. Mum friends saya ada yang turun sampai 6-7kg early pregnancy then gain balik with interest, so jangan terlalu stress lah, tapi do confirm with your gynae ye!