Vaginal bleeding may be a sign of labor. Up to a few weeks before labor begins, the mucus plug may pass. This is normally made up of a small amount of mucus and blood. If it occurs earlier, you could be entering preterm labor and should see your physician immediately at the time.
Signs of preterm labor include these symptoms that occur before the 37th weeks of pregnancy:
Vaginal discharge (watery, mucus, or bloody)
Pelvic or lower abdominal pressure
Low, dull backache
Stomach cramps, with or without diarrhea
Regular contractions or uterine tightening.
Signs and symptoms of pulmonary embolism (PE) include unexplained shortness of breath, problems breathing, chest pain, coughing, or coughing up blood. An arrhythmia (an irregular heartbeat) also may indicate PE.
In some cases, the only signs and symptoms are related to deep vein thrombosis (DVT). These include swelling of the leg or along the vein in the leg. pain or tenderness in the leg, a feeling of increased warmth in the area of the leg that's swollen or tender, and red or discolored skin on the affected leg.
It's possible to have a PE and not have any signs or symptoms.
Sometimes people who have PE have feelings of anxiety or dread, lightheadedness or fainting, rapid breathing, sweating, or an increased heart rate.
Yes, back pain could come from pregnancy, not PE.
I hope this helps you. And good luck.