Dear- thanks for using our service .Diarrhea could be just an acute process secondary to viral infection, food poisoning or bacterial. If it is viral ,most of the time it solves by itself.Blood in the toilet paper could be secondary to internal or external hemorrhoid . However, sometimes it could be from the colon irritation after the acute diarrhea. It is important to check for how long is the problem .If lasts more than 72 hrs, you should see your doctor for a basic checkup which will include samples of the stool for parasite and regular bacteria culture, as Salmonella and Shiguella. The fatigue is due to loss of water and electrolyte so you need to replace the water to avoid dehydration. I hope that my advise has been helpful Dr.Sara