Painful cramping 33 weeks and medication withdrawal? :( FTM

Jen • Mommy to a beautiful baby girl!! Isla Marguerite was born January 2, 2017 at 12:45 p.m. 8 lbs 2 oz, 20.5 inches 💕👶🏼🎀 TTC #2 May 2018! Early miscarriage at 4 weeks June 2, 2018 💔 trying for our rainbow 🌈 baby! BFP July 27, 2018 our rainbow is due April 10,
So last night in the middle of the night I woke up three times to a breathtakingly painful cramp in my whole abdomen. My tummy got all hard and seized up like a Charlie Horse. It hurt so much I had tears and couldn't breathe... my husband helped me out of bed so I could walk around and it didn't go away for about a minute each time. I called my midwife and they want me to go for an ultrasound tomorrow to check on things but I'm confused and worried about what it might be. I'm a first time mom so I don't know what contractions feel like...not even sure I've had a BH contraction yet, but I know they aren't supposed to be painful? This sent a shooting pain in behind my pubic bone and all day today I've been feeling like my muscles ache and hurt from the cramps last night. Has anybody experienced this before?
On another note, Im currently weaning off of my anti-anxiety medication Effexor (doctors orders) so that my baby won't experience any withdrawal after birth. I'm experiencing withdrawal symptoms of night sweats, nightmares and increased anxiety/restlessness at night time. Now I know what I feel like off my medication (been off it before), but I have no idea which of these anxiety symptoms are pregnancy related and which are related to withdrawal! I'm wondering if the cramping last night has to do with this as well!! 
Any input or similar experience would be appreciated.