In December I Experienced Fainting, Low Blood Pressure ( 40/20),

In December I experienced fainting, low blood pressure ( 40/20), low pulse 20, dark brown urine, extremes abdominal pain. This was an "attack" and required emergency attention and hospitalization. At that time and since, no one has been able to diagnose the cause. After the trauma even, two weeks later I returned to the hospital and had blood clots in both legs and both lungs which are being treated with Xeralto. Any idea what the cause of the original trauma could be? I am a 63 year old paraplegic - 45 years post injury in otherwise ver good health.