@Nuna,
Pain can be a result of him being over stimulated, he didn't have sex for a month then seeing the woman he really wants and been fantasying about for a while "but had been forbidden to have sex with till he gets checked" naked.
On a serious note, if he had like 200~300Grams of Walnuts, high amount of Avocado or any other natural "performance boosters" and got really teased by you "given his 1month off sex" it would be quite normal if he got an erection that hurts and ejaculated like crazy.
Make love again in a less intense environment and see how it goes.