I took a long walk yesterday, about 3 miles. I came home exhausted (did it in about 45 mins mostly uphill and pushing a stroller). I took a shower, hydrated with a bottle of water, and relaxed. this morning I woke up sore, so I took ibuprofen, and felt great. At about 4:00 today I took a shower, and started to get the chills. Ever since that shower I have bundled up in sweats and am freezing in 75degree weather. Can I really feel like this after a long walk? I wont lie I'm not in shape and overweight, but I really dont know how something like this can just come on so fast. Any help would be great.