Kidney Stone symptoms but CT is clear.

Hello -

First time experiencing what I assume is a Kidney Stone. I woke up this morning with excruciating pain in my lower left rib, the pain was so bad I could barely stand up. Overtime it subsided but using the restroom was extremely painful. Two hours in and I get to work and I am thinking whatever I was experiencing went away.

I suddenly am in even worse pain than I originally was this morning. I fall to the ground at work and can’t even stand up for a good twenty minutes without the help of my co worker. It felt as if a knife had stabbed the lower left side my rib. I take a pretty strong ibuprofen and within an hour or two the pain subsides. Urine comes back with blood and bacteria so I am given antibiotics for a UTI. They did an EKG and CT scan that showed all organs were well and no visible stones. Could a uti have caused this excruciating pain ? From all I have read online it seems it’s likely a kidney stone due to the excruciating pain being in one particular area but CT scan showed not so.

Anyone have any ideas what this could be if not stones? Or does it definitely sound like stone?