Red blood in stool, shortness of breath, headache, weakness and tiredness all for 2 weeks. Cant carry even 10 kg. However normal bp. Possibe reasons?

See your doctor. Anemia from your rectal bleeding is high on my list of diagnosis. You have to see your doctor asap. The low red blood cell count (anemia) may be causing all your symptoms. Go in today if you can. The reason for your rectal bleeding needs to be investigated.
See doctor. It may be as simple as anemia from bleeding hemorrhoids to colon cancer. You need to see your doctor for an evaluation.