Can bad fissure in rectum (not anal) from constipation cause back pain, muscle spasms, decreased ability to feel stool in rectum, sphincter weakness?

Rectal fissure. Fissures from constipation will cause rectal pain, less likely back pain per se. Muscles spasms are not common except for the muscles in the anal area. Decreased ability to feel stool is possible with chronic inflammation. Sphincter weakness is - "yes".