Remember that once they are eating more food, they will drink less formula as they are getting full from the food. He is 8 months old, and transitioning into foods and occasional whole milk at 12 months. If he's teething, it could be his gums are bothering him, and some Tylenol and/or rubbing some Orajel on his gums could help. There are also quick-dissolving Homeopathic teething tablets over the counter, I believe made by Similsan(sp?) If he's irritable, and just not wanting to take his bottle at all, it could be a sore throat or ear infection. Watch for a temp. if you suspect that to be the case. Otherwise, it sounds like he's getting full off of his food, and to be honest, I had my first baby at 16, and by 8 1/2 months she was eating all the foods and cereals, and I didn't have much money and I went ahead and started mixing formula with whole milk to wean her into whole milk by 10 months. I know no Dr. would agree, but she was fine and healthy. She had no lactose intolerance prior which made it easier, and she was gaining weight and passing check up's just fine.