I think you need to see a doctor. Rectal bleeding with constipation can be a sign of some really bad stuff, you defiantly should get it checked out. (Rectal Bleeding is a VERY important sign that something is wrong.)
I think you should lay off the "cleansing" until you see a doctor. If you are worried about the cost of a doctors appointment, you can call a reputable clinic and ask to talk to a nurse. Tell them you have rectal bleeding and constipation. They will probably quickly give you a nurse to speak with. If they ask if you are a patient, say you are looking to be - and they WILL provide a nurse to speak with.
Do not ignore this and try to self medicate! You need professional advise. EVERY bottle of colon cleans I have ever seen says "if there is any rectal bleeding stop using product and contact a physician."