Plaque and calculus may lead to foul breath. You need to get your teeth cleaned professionally i.e. scaling. You may also need to modify your brushing technique and use other cleaning aids like dental floss and interproximal brushes. Another cause of bad breath may be a carious tooth which acts as a space of food accumulation. A visit to the dentist will surely help solve your problem. Hope this helps!

You may have calculus and food lodgement in several areas in your mouth. This is the first thing to be observed. So visit a dentist for proper consultation and get a scaling and polishing done. This should solve your problem.

Get professional cleaning of your teeth, till the time you get to visit a dentist you can use any commercially available mouthwash.