My son got the same problem ... sometimes. His doctor said he may get gas in his little stomach, so make him dosen't want to 食奶. She recommende us to give Matthew "Infant's Mylicon" (gas relief drop) everytime after we feed him., and she said that Mylicon is not really medicine ... is fiber ... and it is not bad thing. Or my mom said burp Matthew before feed him milk, it also help.
My baby have the same problem. He doesnt like formula much and couldn't finish them most of the time. However, he loves 糊仔. I think u can try to feed him 糊仔 first. so u will know if the problem of his favour or his sickness.