Pain in lower left side??

So my husband and I have only had sex once since I had our baby and he’s 4 months. We used a condom and filled it up with water after we were done to make sure it didn’t have a hole or anything. I know breastfeeding isn’t birth control either but I am also breastfeeding exclusively. So I know I can’t be pregnant.

I’m not sure why this is happening! Could it be a UTI or something? I have been holding my pee sometimes because my baby will nap trap me.. Someone give me opinions! I have an appointment but it’s not until December 4 ): 😕 the pain is on and off it comes up randomly then goes away