Wasn't sure whether to put this under breast feeding or your health...breast feeding it is!

About three weeks after giving birth to LO, my back went into spasms. I was on the floor in pain and couldn't take care of the baby. I went to a chiropractor that night and he told me my back had weakened from the pregnancy and breast feeding (I have a generously sized chest). I went six times and stopped for a few reasons.

LO is now over 9 weeks old and it happened again last night. I breast fed her lying down on my bed and it helped a bit but my back still hurts. Did anyone else experience back issues while breast feeding? Was there a position that worked for your back?