I had 2 unprovoked blood clots early this year, one in my upper calf and one in my lung. I was put on Xarelto for 3 months and had an entire barrage of tests including blood, urine, ultrasound and x-rays, didn’t find a thing. I hadn’t flown for over a year, no injuries and i’m pretty active.
My doctor did mention my lower than normal heart rate and we discussed that dehydration can also put you at higher risk of throwing a clot. At the end of everything no real cause has been identified and the specialist said that there’s a small percentage of people that develop unprovoked clots. I’m off Xarelto now and just taking an aspirin a day.
Good luck with your recovery.