I bet Flex Wheeler doesn't even have health insurance. You only get a limb amputated in the most dire circumstances. Due to the dying of the flesh from prolonged lack of blood flow, he had to have known something was really wrong down there.
I finally watched Dave's interview with Shawn Ray, Shawn says flex was in the hospital earlier this yr for 3yrs (& in a medically induced coma, no less), while they tried to reroute the vasculature.
Ischemia is painful and a problem. (,Shawn also mentioned a severely atrophied calve at Flex's most recent '17 classic physique comp.. it was his left calve, not the one that was chainsaw'd off, btw). If the dude had extreme pain in that leg, due to vascular insufficiency, for months on end, he knew this would be a possibility, much the way any of us with lower leg issues.
Doesn't seem like he had cellulitis, or compartment syndrome, but an issue with blood supply to the lower limb.
People here should maybe open a pathology textbook.