Laura it could be detoxing symptoms from what you describe. If its detoxing symptoms it should not develop into chest congestion like a cold can.
Detoxing symptoms can range from mild aches and pains, allergy like symptoms, low grade fever, sweats, rashes, headaches, fatigue and just generally felling blah for a few days. If some one is very toxic these symptoms can last longer.
Don't overdo the exercise, keep it moderate, get some good sweat in, drink lots of water, blast with fresh lemon, ginger, a little pineapple, cayenne, raw cocao, raw apple cider vinegar and raw honey. This will accelerate the cleanse process and is anti-inflammatory.
I hope this helps,
Wally Bishop C.N.C.