What are anal fissures? Is this something to worry about if I am constipated?

Fissures. Are tears in the anal canal from spasm in the internal sphincter which arises with constipation or chronic diarrhea. Besides causing pain and bleeding, they can get infected and cause abscesses and/or fistulas. They should be properly diagnosed and treated too avoid complications.
Rectal tears. Anal fissures are tears in the anus, frequently caused by straining. Anal fissures can be painful. Treatment is resolution of straining. Nitroglycerin cream can help healing, as can Botox injection. Surgery is reserved for more severe cases.