Burning when hole stretch is too far

Me and my boyfriend have sex a lot pretty much every day of the week but we stop having sex for a well like almost a week and when trying to start having sex again it started to hurt and burn when he put his fingers and penis inside me. But this has never happen before I had him look down there to see if he saw anything that didn't look right and look for pictures after but it didn't look like an type of std had this happen to anyone and what did you do? Ps and I just got tested about a month ago now.