K.L.
The only time my little porker refused the bottle/breast was when she was teething, as another mother suggested. The drooling is a sure sign that, wether or not you can feel his teeth beneath his gums or not, his little mouth is getting ready to cut teeth soon.
Time to start stocking up on teething toys! We had all sorts of cold rings and refrige/freezer toys for my daughter, but she ultimately liked a frozen dish towel and baby orajel. Smear a little orajel on his gums before he has his bottle, and see if that helps. I also used to massage my daughters gums and she seemed to like that, but I don't know if that was something she was just into.
Never fear, this too will pass!