Weird Smell After Sex

I'm on birth control, so I rarely have my SO wear a condom during sex. However, he often finishes inside of me and on some days (please don't judge lol), I'm too lazy to take a shower after doing the deed. The next day or even hours later, when I go to the washroom I notice a fishy after smell. 
​I never smell down there and this only occurs after having sex. I've read about it online and most sites relate it to being bacterial vaginosis. Except after taking a shower, the smell is gone.  
​Do you ladies have the same problem? Is this something that I should get checked?