Are you sure the butter is clean and raw? Does the labelling say it is raw? If it doesn't it most likely is not raw. Throwing up sounds to me like the butter is not ok.
Could be a detox trigger, but you could also just eat less and try to slowly build up. Or switch to another fat source and try again later. You mention it goes ok when you combine it with meat, so that is also an option to eat it. Or make it into a drink with eggs and honey, maybe that will help the digestion as well. I think pineapple also helps well with digestion of fats, so that might be an option.