Epidural back pain

So I’m 16 so of course I’m pretty healthy and my baby is now 6 weeks old and I’m just now having horrible pain up underneath my boobs and in my lower back, now I asked my doctor about it and they said it’s more than likely because I had to get a second epidural cause the first one didn’t work but wouldn’t it hurt before now if that’s what it was??? When I was pregnant I got really big and my back would kill me and that’s the exact back pain I have now but I’m tiny so I don’t understand....anyone else go through something like this?

*UPDATE*

So I went to the ER with my pain and they did an ultrasound and an x ray and finally told me I had gallstones in my gallbladder and just yesterday I had to get it removed....so if your having bad pain don’t forget to get it checked out....I had no idea, I thought it was just pain from my epidural and that’s what my OB doctor said it was so don’t take advice from a doctor that doesn’t know what there talking about