It sounds very celiac. You might want to try the gluten free diet even if the blood test was negative. I tried the diet after a negative test and my chronic fatigue and joint has all but gone
Celiac is often associated with hard stools that can cause tiny cuts. Cuts itch when they heal and this is what i've always put mine down to. I've only been gluten free for 6 weeks and still have very hard stools.