refusing to drink milk

My 8 month old is refusing to drink milk for last 4 days.  He always used to drink his morning milk but now he doesn't want that either.  During the day, he'll probably have 4 bottles with 4-5oz. of milk in each feeding and solids(3 times/day).  I normally mix my milk into his powder formula but in btwn. i used to give him the ready to go formula and he would take it easier then powder formula.  The bottle formula can get very expensive so i went & bought the 1quartz can formula which he took it last night at 7pm & 9pm with no problem.  This morning he refused to take milk at all so we ended up giving him his milk w/cereal and feeding him through spoon.  He was also playing with his bottle & kept pulling on the nipple too.  He's pediatritican wants him to drink more then 20oz of milk in a day but that never happens.  He has always been under when it came to drinking milk.  He was born 1 month early and his weight was 5pound 6oz.  He acts normal, he plays normally, he's happy baby but his only problem is and have been when it came to drinking his milk.  It's really frustrating for us and don't know what's going on???  Does he have any internal problem??  Does he need to get his upper G.I. checked??

[Renee Radenberg]

Have you tried changing the brand of formula and seeing if he would accept that instead?