My girl has the same case as you. She was very sleepy in the 1st month and did not cry even she was hungry. Her bodyweight continued to dropped for the first 21 day and gained only 0.45kg in the 1st month. I needed to take her to hospital for blood test everyday. Her body weight dropped but the 'yellow' index increased. I finally supplemented with formula and her case was then transferred to 'medical center' for follow up when the index dropped for a few consecutive days. Her last 'yellow' follow up was on the 2nd month when she received vaccine.
If you could remember, I am also 0904 mom. Have PM you my contact in case you need further info. Add oil and don't worry too much.