Thin stool for one month. Blood test!

I have an issue from past 1.5 month of having stool which is thin in consistency floaty and doesn't have body to it .I do feel sligh discomfort and presusee sometimes while passing and sometimes slight pain after finishing it.  Once I have urge I have to go it seems and frequency is increased like 2 to 3 times a day although I have history of improper stool constipation, bloating and haemorrhoids and one year back had gotten a proctoscopy done  for minor bleeding issue due to fissure  which dint indicate any cancerous issue  but thin stool is unusual . I have heard of thin stool being symptom of colon or colorectal cancer can you please guide anyblood test intially to rule out possibility like the CA marker cea blood test