I'm not keen on going to the GP unless really necessary, so I'll ask for any ideas here first.
It's happened twice now. Basically I'll experience a mild backache for about 4 hours, it will then go away for about half an hour, until I make a sudden movement such as standing up or leaning forward as there will then be a massive spasm in my mid lower back. It is first a sharp pain then a general stiffness; I won't really be able to move without pain for a minute or so, around this time its also quite difficult to breath, exactly the way you feel when you get winded after a blow to the back. Its basically like the feeling you get after you get hit in the back with great force except there is no force. After all this happens it's fine when I'm sitting down although a bit painful when moving.
I just treat it with rest, a hot water bottle and some painkillers and the pain goes away within a day or so. I don't want to waste the doctors time but if needs be I will go, at the minute I don't think its serious enough. Basically what I'm asking is, do you have any idea what this is or what causes it? I'd like to avoid it where possible in the future.