Welcome to HCM.
Coxsackie virus infection can result in various presentations which can range from common cold
like illness, hand foot and mouth disease, brain fever
etc. In your case I am suspecting a rare presentation called as post viral fatigue
syndrome where there is generalized fatigue and pain which usually occurs for years after Coxsackie infection
. This can be managed only by healthy diet and exercise.
But if you are losing weight and then gaining it back then hormonal
disorders have to be ruled out.
I would suggest a healthy diet, regular exercise and an endocrionologist opinion for the fluctuating weight.