Contractions?? 36 week's

Everyone always post you will know and laughs it off but it doesn't help for FTM. So can someone please explain what they have felt like to you please. I'm pretty decent when it comes to pain and tolerating it so its hard to judge at times. I've had serious period cramps and had to go to er bc u thought something serious was going on and now I really can't tell.I'm 36 weeks today and the last three days I've had bad bad cramps that come and go consistently all day and see to be getting worse. Last night it woke me out of my dead sleep.I can't get ahold of my doctor and I have a appt in the morning but is it normal at this point or am I having contractions.I can barely walk and cringe at the pelvic pressure and want to cry sometimes bc my back hurts so bad.