Bleeding from anus will be due to many causes,but commonly from Piles (Haemorrhoids) & Fissure in Ano
If the bleeding is associated with pain in the anus,it may be due to fissure in ano.
Bleeding from anus while urinating may also be due to piles.
But,the diagnosis will be confirmed by your clinician by clinical examination.If he has doubt,he may ask for Colonoscopy
Ultrasound may also give a clue to Stomach upset
.If it doesnt conclude,then you may have to go for Upper GI endoscopy
But,everything has to done under the guidance of your Doctor.
Hope everything will be alright.
All the best