Second, it could be that he is being "hard" at the act, pushing deep, fast and he could be cutting you...
This is all a gentle thing, should be totally enjoyable taking you to heights.
Mae, you say that he was into "very heavy petting" so he may be doing it all wrong, being totally aroused and not understanding that you have to be gentle yet, on-going over a longer period of time to make it get you where he wants you to go, he may in other words be in-experienced.
Ask him to do it slowly, and deep, see what happens.
It is likely that he is pushing with "gusto" and well you won't feel that at the time if you feel great about it.
Try that first.