I completely agree with Meoshia, if he is eating wet food ok that may suggest the smell stimulates him so much that it is over coming any settling in jitters that are causing him not to want to eat. If you are set on feeding him kibble then you can try adding low sodium broth to the kibble to try and stimulate him. Ofter in the end, old fashioned hunger wins out but when they are tiny you have to be so careful with hypoglycemia, so do keep something on hand and know the symptoms.
Wet or dry it really depends on what you are feeding him as to wether it is good for him, sadly so many dog foods are full of cheap, indigestable fillers, the two websites above are excellent places to find solid information on what you are feeding your pup. There are some excellent and affordable 4* & 5* foods out there. As Chi's only eat such a small amount it is so very important to ensure that that little amount is packed with the best nutrition possible, looking into those websites will help you to ensure that
good luck and keep us posted!