Anyone know what kind of bites these are?!

They itch horribly and they are on my butt cheek lol

It started Sunday evening after we went swimming at my grandmas pool. It felt like something was poking me on the butt through my jeans. Like a piece of grass or something. Monday the area just started itching. Tuesday it was itchy with a massive hive and today it’s itchy but there are several bumps?

We don’t have any pets & I’m constantly vacuuming our floors so I’ve ruled out fleas. We definitely do not have bed bugs. My husband and 2 year old daughter have nothing on them. I was thinking maybe ants?