Regular blood in stool. For this?

Hello Doctor, My daughter is 21 months old. She started suffering from constipation as soon breastfeeding was stopped i.e., when she was 6 months old. Initially we consulted pediatrician and there was relief until she was taking medicines. Once medicine is stopped the constipation is back. We consulted Homeopath as well as Ayurveda doctors also. The issue is, constipation starts again as soon as medicine is stopped. Her stool is very tight, almost black and blood is spotted in the end since last 15 days. Yesterday the amount of blood was more. As suggested by doctor we have done ultrasound today, but everything fine as per doctor. He suggested to give "MuOut plus powder" for 15 days. We are managing her diet for last 6 months, not giving outside food or milk, giving seasonal fruits, suji, daal, messed vegetables, apple, figs etc but nothing works. Can you please suggest regular blood in stool can have any affect on my baby? Should we visit you or any specialist for this? Thanks Sir.