My 7 Year Old Toy Poodle Has Blood In Her

my 7 year old toy poodle has blood in her stool the recue she came from says she was dianios withsomething calledDiverticulitis and she would have to go n specail dog food the rest of her life .she was eating yams intestial puppy food which i feel shes still have too much bloody stool so I have whiced her to Nutro lite the pet smart people recommed ed is there ant thing else I can feed her to control the bleeding she in no pain and appears to be happy the recue says she; been bleeding for a long time ..what do you think I cant afford to pay a fee could anyone hepl me