Do you enjoy your Japan trip other than take care of Adonis? It's a good place anyway, clean & tidy and the weather is now quite fine. You can enjoy more if Adonis is 1 to 2 years older. Myko also don't have anything except milk & bread during our last trip at Kota Kinabula.
Do your son regularly wake up & have to drink milk during mid-night or just because your helper has gone? May be just because he is not familiar with the new condition. You are capable & easily to handle it!