What Causes Severe Pain In Lower Back Shooting To Spine And Neck After Childbirth?

6 weeks ago i had a baby by c-section. during my pregnancy i had pain in my lower back that shoots straight up my spine and to the base of my skull making me feel temporarily paralyzed and in in blinding pain. i figured it was stress and went on reduced work hours and then early maternity leave. after having my baby they have been more frequent...three in the last week alone. while i am short of stature and over weight, i have been actively losing weight (am now 30 pounds lighter than my pre-pregnancy weight) i have not had any high blood pressure issues after my baby was born. what could be causing this and is there a need to be alarmed?