Threatened Abortion: This is the most likely diagnosis given the patient's symptoms of spotting and cramping at 5 weeks of pregnancy. The presence of a small amount of blood and mild cramping are common symptoms of a threatened abortion, which is a condition where the pregnancy is still viable but there is a risk of miscarriage.

Constipation-related Hemorrhoids: The patient's report of constipation and harder than usual bowel movement could lead to hemorrhoids, which might cause spotting of blood when wiping after urinating.
Urinary Tract Infection (UTI): Although less likely given the primary complaint of spotting during pregnancy, a UTI could cause discomfort and possibly some bleeding, especially if the infection has moved up the urinary tract.
Cervical Polyps or Erosion: These conditions could cause spotting, especially after sexual intercourse or with cervical movement, but are less directly related to the pregnancy itself.

Ectopic Pregnancy: Although the patient is only 5 weeks pregnant and ectopic pregnancies are more commonly diagnosed later, missing this diagnosis could be fatal. Ectopic pregnancy can present with vaginal bleeding and abdominal pain.
Molar Pregnancy: A rare condition where the placenta becomes abnormal, it can cause early pregnancy bleeding and other complications.
Placenta Previa: This condition, where the placenta covers the cervix, can cause painless vaginal bleeding but is less common at 5 weeks of gestation.

Ovarian Cysts: While ovarian cysts can cause pelvic pain and could potentially rupture leading to more severe symptoms, they are less directly related to the symptom of spotting during early pregnancy.
Gastrointestinal Issues: Other gastrointestinal issues like anal fissures or rectal ulcers could cause bleeding but are less likely to be directly related to the pregnancy and the specific symptom of spotting.