thank you for your query.
it seems you are suffering from inflamatory bowel disease exactly Crohn's disease?. Pentasa
is a good choise for inflamation of terminal ileum
. but the natyre of disease is with periods of calm and periods of irritation.
symptoms like blood in stool
show that that your bowel is inflamated now .
so I would suggest to see your gastroenetrologist to rise the dose of pentasa or to add another drug.
All the best