Did my son get injured during his exam?

This may be long but I'm just struggling to understand exactly what happened and I want to make sure I'm correct before running my mouth.Basically my son had his 18 month checkup with a Nurse Practitioner, not his regular doctor (out on medical leave). During his groin exam, we had him in my lap, back towards my chest because he doesn't like the exam table. I couldn't see what was being done. I know his regular doctor only checks for descended testicles and hernias so I wasn't worried. But now I strongly believe she retracted his foreskin injured him. He was crying the whole exam so I didn't notice anything at the time.Once out of the exam, we went home, played for about an hour and he was fine. I dropped him off at my MIL and went to work. About 4 hours into my shift, my MIL calls me at work saying she wants to take my son to the ER because his penis is very swollen and red and he's screaming himself blue in the face over it. I meet them at the ER. The doctor said there's a rip in his foreskin.Now, I was always told with a "natural boy" to NEVER retract his foreskin until he is old enough to be potty trained or is able to do so in the bath on his own as a part of cleaning. His foreskin has never been retracted before. He has got erections numerous times with zero issue in terms of "room to grow" in there or tension. He's touched himself in the bath numerous times and has never caused injury. This is why I'm growing confident it isn't something he's done to himself accidentally. It was about 5 hours between the exam and my MIL wanting to take him to the ER.Am I crazy for thinking the nurse injured him? Has this happened to anyone? What should my next steps be? I've never been in this position before and other than sit here and be mad about it, I really don't know what do to. via /r/Parenting http://ift.tt/2l4xcKt