I am an elite distance runner mainly 10k and shorter and over the last 2 months have been feeling really tired and unable to run much. I usually run around 4-13 miles a day but lately have had trouble even running 2 miles. I collapsed in a 400m from the finish in a 10k a month ago and was told I was incoherent. I had a-fib and my pulse was above 120 even after stopping for over 20mins. I went to the doctors and was told I was fine and ell my blood tests came back normal- no abnormalities in iron levels or thyroid etc. I have been noticing that my hands go white and tingly tho only when i run. I had an echo done before christmas this year and that was also normal. doctors I have spoken to think I have raynauds but I am still not sure if this is connected to my fatigue or why it continues to effect my running even though I wear gloves and the weather is approaching 70 degrees. I have also put on over 10lbs in the last week but have been eating healthier recently. Have you any ideas where to go next in my search for what is wrong?