After swimming in the chesapeake bay ocean after a couple of hours i notice a red swollen bump on liba whole right side is swollen what is it?

Jellyfish likely: Your description sounds like a jellyfish sting. If so, first, take sticky tape to the red area - there may be cysts left that can still fire venom. Then hot water to area (sit in a hot tub for labia injury). Then take pain meds (like Advil). Also, call local public health department to ask about other reported stings and their recommendations