36 weeks pregnant with hardly any movement today!!?

Hello..just a quick question...I don't want to be a paranoid Mommy but my little guy is ALWAYS moving around feeling like hes going to burst out...I am 36 weeks and 2 days pregnant and in the past 2 days I have had a horrible backache and today felt my first sign of "period like cramps" along with hardly any fetal movement. I drank two huge cups of OJ and laid on my left side to reure myself but he barely moved 2 or 3 times in that hour I was laying down. Should I wait till tomm and call my doctors office or do you think I should call the hospital? I guess Im just paranoid that the cord is around his neck or something could be wrong...just looking for some guidance! Thank you!