From my neck all the way to lower back has all of a sudden started hurting worse than just at night…

From my neck all the way to lower back has all of a sudden started hurting worse than just at night like it's been and I'm having menstrual like cramps or a lightening crotch like feeling. Is this the start of labor? It's pretty constant... I'm home alone and this is my first baby I don't know what to do or think? Please help I'm 36 weeks now