I Have Weird Tummy Pains, It's Been Happening For Quite

I have weird tummy pains, it's been happening for quite a while now but comes and goes so I don't think anyway of it but when it happens it's worrying. I get really bad cramps and the bottom of my stomache to which I'm almost in tears but I don't move and just kind of stretch it out. I also get a dull achy feeling in my tummy and when I press it feel bruised, what could this be?