Thank you for the query.
Fresh, not mixed blood in stool
is most often caused by hemorrhoids, so you should not be so scared. Especially that your work forces you to sit for many many hours. I suggest you to visit a surgeon and have rectal examination
might be necessary, but only to definitely diagnose that this are only hemorrhoids.
To improve your symptoms, you should avoid constipations, increase fiber rich products and mineral water intake, avoid fatty foods and soft drinks. Physical activity should be also very helpful.
Sitz baths with Quercus Cortex
and hemorrhoids suppositories should help as well. Such treated hemorrhoids should stop bleeding and partially disappear in a week or so.
Hope this will help.