I'm about 18 w 2 days on for about a week now bin getting crazy sharp pains every so often on my tummy all over some are so. Bad at times they fold me in half I've bin reading things online saying it OK an every thing but is it this is my 4th child and I've never felt this before

This is your child, if you think something is wrong, don't wait for it to get better. You know your body, if it hurts and isn't like what you experienced in other pregnancies go see your doctor, or at lease give them a call - better safe than sorry!

Cramping at 18 weeks is fairly common though, it's caused by stretching of the round ligament which holds your uterus in place. This is sometimes expressed as sharp pains on either side of the stomach which can become severe.
But, like I said if it's really bad, call the doctor.