Lot of Blood with stool with no pain.?

2 week ago I have lot of blood (never come again til this post) come with stool I go to emergency hospital they give medicine and cream for my Anas for week and told me to go to OPD to meet a surgeon I did Dr. look at my Anal not even touched me and suddenly said I have anal fissure I said to him that I don't feel any pain if I had fissure I should feel pain he said don't worry some time it's only itch . So I said ok but from last 3 weeks (from the starting) I have constipation then suddenly one time diarrhea then constipation again I go to emergency hospital they give me medication and I also loss 2kg weight. Any of this is series or I continue my medication and creams given me by the Dr for months to take or visit him gain or is it common to have no pain in anal fissure and have constipation..?