What Could The "pop" In The Groin Area Be?

The other day, hours after a workout, I was walking around my house when all of a sudden I felt like a bubble made it's way up into my groin area (right where my leg meets my hip). It feels like I need to "pop" it just like when an air bubble sneaks into my ankle and I pop it by moving my foot around. It's not painful or anything, just a dull pain I suppose, and it's very annoying. What can this be?