Formula help

We have started my 5 week old DS on novolac reflux formula he has had 2 bottles so far. After his first bottle he was so happy and content a completely different baby, he even made it the full 4 hours. After having his second bottle completely different we are back to a pissed off baby he was grunting and squirming while feeding crying and arching his back after his bottle as well as passing a lot of gas. Oh and another weird thing he kept sneezing for around an hour after his bottle. I have a doctor appointment on Wednesday but my question is - is this an indication the formula isn't working well with him or do we need to give it a few days?