Does anal fissure or what disease cause headaches / stress / loss appetite / itchy after stool / sometimes blood in stool / stressing out about it?

Different conditions: An anal fissure or hemorrhoids can cause blood in stool and anal pruritus or itchiness. The headaches and stress may be due to a different condition. A possible link would be through a degree of anemia if the rectal bleed has been going on for a while. Stress is the disease of the century and lifestyle changes are usually necessary. Talk to your doc about your symptoms at next visit.