Why haven't you gone to the doctor before this? It sounds like an intestinal infection which would require a stool sample to be sent to the lab. It could also be IBS (although that does not generally get you up by night) or Crohn's Disease. There are many other possibilities but you really must see someone asap before you become run-down and lacking in essential minerals. Please drink plenty of fluids in the meantime as dehydration can become a serious problem after this length of time.