Suggest Treatment For Rectal Bleeding When Having Hypothyroidism

Hi I have hypothyroidism I was born with this condition I am now 28 year old nd have been medicated for a year. For the last 3months I have been bleeding from the rectum. The hospital I attend have seen me once since diagnosis and keep putting my appointments off and I m terrified of telling my doctor. I m on 15mg of carbimazole a day and given propranalol to stop my body tremors however this has increased. How do I go about this and do I inform my doctor of the bleeding. I have children and extremely scared