For the past two days, my 3 months old daughter has been refusing to drink milk. Normally, she could drink 3 oz at 3 to 4 hours interval. But now, the moment we put the nipple into her mouth, she screams and cries. She doesn't have fever or elevated temperature, and is active. Once in a while, we succeed in tricking her to drink the milk while she was sleeping. She is currently only drinking about 10 oz a day. Is this something that I should be concern with?