20 weeks, intense back pain

It's not really a rant. I woke up this morning feeling okay, and then about 2 hours after waking up, I started feeling deep cramps. Usually, that means I need to go to the bathroom, i did go but it didnt ease up and quickly radiated into my lower back and that didnt ease up at all. The cramping would come and go, but the back pain didnt stop, it hurt really bad. I also wasn't feeling baby move, I know they don't get consistent until 26-28 weeks, but for 3 weeks i've felt her some in the morning and a lot at night.
I decided it might be best to get checked out for peace of mind. Baby's heartbeat was good and while laying on my back she started kicking like crazy. My BP read 90/44 at one point but quickly came back up to 103/60. The cramping eased up, and the back pain pretty much went away. I hate over reacting and going to the ER for nothing. I mentioned feeling lightheaded and dizzy randomly, and extreme tiredness. I havent seen my OB in a month, and when I googled it, it told me it was usually normal. They told me to call my OB tomorrow to be checked for an iron deficiency, I had it with my first pregnancy and they said it's likely i'll devolp it with this one.