Wow sounds like what happened to my almost 5 month old a few weeks ago. She use to take 6-7oz then she started taking 3oz and when she didn't want anymore she would bite down hard on the nipple. Finally I bought some orajel, put it on her lower gums 15min prior to feeding. That feed, after 2 weeks of 3oz feeds, she finally took a full 7oz! Mind you she stopped first at 3oz, but I waited 5min, then tried again and she downed it. Unlike before where even if I waited 15min she would refuse to try again. I used the orajel for about 4 days, then I think the teething symptoms stopped and she is now back to 7oz feeds without orajel. I hear the teething symptoms can come and go months before a tooth shall arrive. She didn't exhibit any other symptoms. I would really try the orajel though.