Severe back pain on Accutane. Should I just stop the Accutane or go to a lower dose?

I'm a 28 year old female in the middle of my 3rd month on Accutane (first month: 40mg, second and third month: 60mg). So far the only side effect I've had is the dry lips and skin but last week I was just getting ready for bed and my back buckled, and I fell to the ground on my knees. Since then, I can't bend over and I'm in a lot of pain - it's been 5 days of this. I'm assuming it's the accutane because there's absolutely nothing else I can think of. My dermatology checkup is tomorrow.