Aih, 5kg tu dah quite a lot lah, mama! I'd say check with your doctor first sebab takde selera boleh jadi sign of something, especially kalau berat turun dalam short time. A few of my mum friends went through this post-pregnancy and one of them turned out kena deficiency, after blood work and supplements, appetite dia balik! In the meantime, try makan sikit-sikit tapi frequent, minum plenty of water, and prioritise nutrient-dense food kalau boleh, macam eggs, oats, soup, tak perlu makan banyak tapi buat setiap gigitan count, especially kalau you're nursing.