Im 10 months postpartum... I went to doctor complaining about back pains

The doctor came in the room and told me no infections/he doesn't know why im having back pains

The doctor said he was giving me something for pain.

The nurse came in an offered me 2 prescriptions I asked her if I dont have any infections why do i have a prescription for antibiotic

She went back and checked an came back and said oh it looks like you have a bladder infection.

I dont believe them

I just feel like something isnt right Ive had bladder infections before I never felt like this

Should i listen to the doctor and let my theory go or get a second opinion