Reflux definitely doesn't have to have chucking as a side effect. (Not does chucking mean reflux. Happy chucker a come to mind) Many babies have silent reflux, and a sign like arching back shouldn't be ignored, as it often means bub is in pain. Definitely get a second opinion. Perhaps see if you can get DP to record what he is doing during a feed so you can show the gp rather than trying to explain it too. DD had some problems as a bub, and they were brushed off the first time I mentioned them, cos they weren't happening right at that time. So I recorded something to show and was taken seriously after that.