Hi, I m 37 and training for a 30k race, which I ve never done before. I m not a fast runner, but I love it. After my long runs, I keep getting fevers that last for several days. I feel unwell too. Why is this happening? I m now tapering and running shorter distances (15k) on Sunday, but I still have the fever and muscle aches. I m worried about wether or not I should do the 30K in 2 weeks.