How To Get Rid Of Foul Body Odor?

Hey, i have recently started to have an unmistakable body odor that smells very bad... i havent changed any of my patters, shower 1 or 2 times a day, brush often, and wear clean clothes every day. I have also had troubles with the bathroom, passing gas, and headaches. What could this be caused by, how can i stop it? It is anything serious?