Final answer:
The symptoms mentioned can be associated with various conditions, with the signs most consistent with an ectopic pregnancy. Concern for pregnancy after unprotected sex followed by ovulation pain is valid. Minor bleeding and cramping three weeks post-period could be implantation bleeding or a sign of complications.
Step-by-step explanation:
The symptoms described in the question (pelvic pain, abdominal pain, vaginal spotting, or light bleeding, missed period) can be indicative of several conditions including early signs of pregnancy, urinary tract infection, ovulation, but most consistent with an ectopic pregnancy. Regarding the scenarios provided, a woman engaging in unprotected sex on Saturday night and experiencing mid-cycle pain on Tuesday could be ovulating, making the concern for potential pregnancy valid as sperm can live inside the female reproductive tract for several days. Additionally, a woman experiencing symptoms three weeks after her last menstrual period could be dealing with implantation bleeding, which can include brief episodes of cramping and minor bleeding, or possibly the onset of a complication such as an ectopic pregnancy.