Thanks for your query. Trimmers never cause blood in the stools, please get evaluated by a surgeon, it could be due to HEMORRHOIDS or just a fissure-in-ano, and get your stool also examined. Dont ignore this symptom. Mean while have plenty of water and take lot of fibre diet, avoid fatty and high carbohydrate
diet for some tome, you can use some stool softeners also.
I hope this information has been both informative and helpful for you. In case of any doubt, I will be available for follow ups.
Wish you good health.