Feels like I have to pee, but only when walking/moving. What could this be?

[DesereeR]

I'm 27, female, good health, sexually active with one partner, using birth control, never been pregnant. Last month, my period started a week early even though I take my pills on time. The week after, my period continued as it normally would have. One day I had severe cramps and once they subsided it started to hurt to pee every time I used the toilet. Doctor said UTI, gave me antibiotics,  and the burning went away. However, what hasn't gone away is this strange tickling feeling almost like I have to pee, every time I stand up or walk. It feels as if there's a giant gas bubble in the left side of my belly pushing down on my bladder or urethra, bouncing as I walk, causing this sensation. I was extremely gassy and assumed this was caused by the antibiotics but it hasn't stopped. Two months ago I had an ultrasound for a different medical condition and there were no fibroids at that time so I don't think that's it. My UTI is gone, so I don't think that's the problem either. I'm also a powerlifter, and was squatting heavy the day all of this started, and I'm scared that I may have prolapsed something inside of me that's putting pressure on my bladder. I've been told that is unlikely due to the fact I've never had children, but I just don't know what could be causing this horrible feeling!