Baby ate 2 jars of pears successfully, now will not touch baby food?

My son is 5 months old and his doctor said that it would be ok to try him on stage one baby foods. We started with pears as was recommended by our doctor. He LOVED it, gobbled down a jar a day for the first 2 days with no trouble at all. Ever since (about a week and a half) I have tried every day because they said to keep them on the same food (if they actually eat it) for 4 days before switching foods. But now every time I give him any, he just spits it out and acts very uninterested... do you think that maybe I should try a different food? Maybe he just doesn't like pears.. I'm making sure he's hungry when I try but he just doesn't want the pears. What would you do? Thanks.