sorry to disappoint you snaggs,
I know i,ll have to go to vet but I,m frightened she says something bad, thats the reason I asked here first, incase someone's dog had anything similar.
The mucus indicates collitiis, which is easily cleared up with antibiotics. The blood is probably just from her straining to pass the poo.
Please never avoid visiting the vet because you are afraid what they will do - vets are not in business to kill dogs unnecessarily, they want to help cure them so they continue to be customers! Also if your dog was really ill or in pain, wouldn't you want to relieve its suffering?