By the way, I was not swimming. I just wear them around the house sometimes.
If the swimsuit wasn't wet, it was probably just irritation from the fabric. If it was wet or you got really sweaty, it could lead to a fungal infection, but there are over-the-counter creams for that. You'll know if that happens because it will itch a lot.
More likely just irritation, though. Give it a break for a few days and see if it goes away. (and please do not upload pictures of your genitals here - it's not allowed.)
Maybe, that irritation and redness due to the harsh fabric. You can apply any skin allergic lotion into it. If you are feeling a severe problem, you must visit a dermalogiost.