This started last night as I was just sitting on sofa watching telly. Been coming & going all day, mostly when sitting down. When I had tea I had to stand up to be comfortable. It really hurts when it starts & feels like it goes thro to my back. If I'm up &walking about its mainly ok. It's on my left side & hurts if I press bt also just starts out of the blue. Anyone had similar? What could it be?