I'm 29yo, no medical conditions, no medications. Recently I became sexually active and I found that during doggy style sex, in the specific spot around 1 inch up and to the left of the place where penis connects to the body (https://i.imgur.com/kfyTwB8.png) (from my perspective) every single time I start to feel pain that begins as just slight discomfort every time my partner's bottom hits my genital area but then gets progressively more unpleasant until after merely a minute or two it's painful enough to steal my attention completely and feel as if I kept pressing on a bruise in that spot.
I never felt this cause any problems in my life beforehand. I don't experience this discomfort in other sex positions either. Even when I want to deliberately cause it now, I need to press pretty hard on that specific spot so it seems weird to me that a mere clap of my partner's bottom after every thrust would be enough to trigger it, let alone make it painful enough for me to stop enjoying the position.
Is it because of some muscle there? I'm an avid runner and run aroung 40km a week while being rather heavy (90kgs/180cm) so maybe this can be putting some strain on that spot? I don't even know what the culprit may be cause that area feels like one big muscle to my touch and nothing is out of ordinary either by touch or by the look of it. Even when I press on that specific spot to make it sore, I can't even feel under my fingers _what_ exactly is sore there.
I thought about hernia but one thing that doesn't seem righ about hernia is that neither do I have any external signs in that spot (though I know these don't always appears) nor do I feel any discomfort during any sports and like I mentioned, I run quite a lot. Climbing, running for well over an hour - no discomfort whatsoever, so I reckon it'd be weird for it to flare up after 30 seconds of sex?