Please, please can anybody help me? Am training for Sheffield Half in 2 weeks. Training was going really well until last week when I caught food poisoning. didin't run for 4 days then eased back in. However when I return from a run, usually when I go to bed, I have get these pains in my legs. Not sure if is the muscles/ joints. The pain is so bad I have to get up to take pain killers but is completely gone by morning.