Rice cereal problems

Ashley
Before anyone says anything negative I was given the go ahead from pediatrician on both. She told us to start giving my son rice cereal in the bottle (for reflux) 10 days before he wS 4 months old. Now that he is 4 months she said to go ahead and give him rice cereal by spoon. He has been doing good with it this is his second day but tonight he has been extremely fussy and seems gassy. He has all the other signs of being able to handle food. So my question is has anyone had this problem of their baby being really gassy after having rice cereal by spoon? He has been on rice cereal for a total of 12 days now.