sudden pain and cramps at 31 weeks?!!

Kay
So since last night I have had the worst lower back pain ever 😩 including pain in my bottom. I was struggling to get out of bed after resting for a while and I struggled to walk. I thought maybe it was due to me cleaning up and tidying my clothes.. but i didn't lift anything heavy. I slept the night with having to go pee every 2 hours and every time I got out of bed and to the bathroom, I was in immense pain. I felt so much pressure down there when I walked and struggled to get my self down on to the toilet seat. 
Today I feel 10 times worse. I tried walking to see if it helps the pain but I can't walk without making a screwed face. I sat down for a while which didn't help. I'm currently laying down on my bed and my legs feel so heavy and I have an achy pin in my groin. My stomach has felt like it has been cramped all day. My indigestion and heart burn has gone worse for which I'm now on tablets for. Should I be worried?Â