I am sorry to hear of this severe problem, and it certainly sounds like you need to see a specialist, preferably a gastroenterologist.
I think you might be having some degree of severe bowel spasm intermittently, this will definitely cause the cramping you are experiencing; there are a couple of natural remedies you can try, maybe they will help.
Take regular aloe vera to reduce bowel inflammation, and peppermint oil is a natural antispasmodic that is both safe and effective.
As I stated at the beginning, if this continues, then it is important that you see the specialist, it may be nothing serious, but it always to err on the side of safety.
I hope you feel better soon.