How do you convince husband to get checked

My hubby has some...odd physical differences in his genitalia then a lot of other men have. His sack is........ Bumpy!!!! Like not a ball at all it feels like one of those squishy balls with floating stuff inside. But because he's 100% stubborn and he wont get it checked out. I mean don't get me wrong it doesn't bother me. But because it doesn't look normal concerns me because i don't want him to have anything wrong with it. I don't want something to happen later on down the road. We've been TTC for 8 months now and I'm starting to get worried neither of is can have kids. I'm trying to go to A dr soon. What should I do to get him to get checked