A bad taste in the mouth can be caused by many things, such as...kinds of food you eat, certain drinks like coffee, if you're a smoker, medications you take, an empty stomach, etc. Have you ever tried brushing your tongue also? I always do that when i brush my teeth. So many germs and bacteria lie on your tongue and can cause bad breath and a bad taste in your mouth. Also, just because you have a bad taste in your mouth, doesn't mean you will be sick or v*. Also you can try those Listerine Pocket Packs, i use them a lot..if i feel yucky in my mouth, i pop one in! It freshens your breath and kills the nasty germs.
For God has not given us a spirit of fear; but of power and of love and of a sound mind. 2 Timothy 1:7