The last few days DS has been very reluctant to feed from my left breast. He used to prefer this one to the other. He either screams when I try to latch him on, or comes off screaming after about a minute. He's also been trying to shove his fist in his mouth quite a lot. He's just over three months. I know this would be quite early for teething but I just wondered whether sucking on my left breast could be painful for him due to position of any new tooth coming through? Or is this a load of cobblers?