Could be either. Are you home now? If so contact the midwife and ask them to send off a urine sample, if you’re still in hospital, mention it to them prior to discharge and ask them to do the same
It wasn’t post c-section but post my fallopian tube being removed I ended up with a catheter in for 3 days and once it was out ended up having issues with burning and feeling like I wasn’t emptying my bladder for quite a few weeks, it did eventually settle!
I havent had a c section but i did previously have an operation that required me to gave a catheter, i experienced intense burning but it went away after a few days.