My stomach does a weird pulsing, what is wrong with me?

Recently I've been getting a weird pulsing/contracting(?) towards the middle to left side of my stomach. It's right under my ribs.It doesn't hurt but feels really weird.The only way I can describe it is as a pulsing.It just makes me a little worried it could be something serious.Can anyone please help? Serious answers only please!!My stomach does a weird pulsing, what is wrong with me?
Well, if we rule out a baby kicking, it sounds like a muscle spasm. I don't think those usually last overnight, so it could be from stress or a muscle injury.
It's best to consult a professional like a doctor because you'll be able to be certain about your case. But if you don't have access to one then I would suggest you ask an expert at http://en.allexperts.com/ . Good luck!
It could be the start of your period. Has it happened before? Did you get your period within a few days of it happening. I would consult a doctor just to make sure.