feels like I have to urinate every 3 minutes

I've had an issue for a little over a week now, and I ended up going to an after-hours facility to get it checked out. It seems I have to urinate within a minute of walking out of the bathroom from urinating. If I hold it, I can usually go about 2-3 hours, before I HAVE to go again. Unfortunately, when I do hold it, it feels like there's a few drops coming out on and off for about 15 minutes. I was told I may have a UTI, and was given 3 pills/ 2 different antibiotics. The frequency dropped quite significantly, but I still feel as if I'm going, when I'm not. It's very uncomfortable, especially when I'm at work.
On a side note, since all of this has started, it feels as if I have a balloon in my stomache that's slowly inflating. Almost like really bad gas I guess, I can take Maalox, and it's not as bad but it's still there. I told the after-hours doctor, that I had some pressure, and she assured me it was the UTI. It's not just below my naval anymore, it's the whole stomache area.
As for differences in my daily activities, I've only been lifting weights and using an elliptical, whereas 3 weeks ago I wasn't.
I'm a 22 year old male, and this is kind of embarrassing.
Any advice I can get would be great. Thanks :)

[Dr J Singh]

Hello,
Frequent urination in adults can be due to many causes. The primary cause which needs to be excluded is diabetes. Diabetes not only causes frequent urination but also numbness and tingling sensations. I would advise you to get a fasting blood sugar and Hb A1 C test done.

If diabetes is ruled out then other possibilities which need to be ruled out are prostatitis (inflammation of the prostate gland), interstitial cystitis, overactive bladder syndrome, stroke and other neurological diseases, urinary incontinence, bladder cancer(rare) and bladder dysfunction .

Please consult a urologist in that case.
I hope it helps. Take care and regards.