HI thanks for asking question in HCM. According to history given you have only muscle pain and headache. It seems most likely viral infection. But symptoms severe, so better you first do your CBC examination and LFT. If CBC show lymphocytosis then it will surely viral infection. But if neutrophil increased then possibilities of bacterial infection. The CBC can also reveal malarial parasite if present(associated fever present) LFT is to rule out early stage of hepatitis infection. Here if bacteria infection is cause then we will start antibiotic.Otherwise for viral infection treatment is symptomatic. Drink more water in a day because it has antioxident property. Eat more fruits in day time.Heavy fatty meal is to be avoided. Take enough rest.And take healthy nutritional diet with green leaf vegetables. For pain relief take simple analgesic. Mostly within 3 to 5 days you will recovered.If still no benefit then we will do further work up. Don t worry.thanks.