12 week old nursing difficulties

manderdoll

My 12 week old is EBF, he is a very big boy 19.8lbs already, he seems to be on a nursing strike.  He fusses, won't stay latched, pushes away from me, makes his body go stiff.  This is day 4 now and I'm not sure what or if I should do anything.  I know he is not in desperate need of gaining but he still needs to eat, he's going almost all day without really eating.

Has this happened to anyone else?  Any ideas or suggestions?

DS1 has been very slow with his teeth so I don't know if teething would be the problem.