I would strongly recommend that you go and see a dentist to sort this out for you. Please do not feel embarassed as we are used to seeing dental problems and are here to help you.
Once your teeth have already begun to decay, only a dental professional can help you with this by treating or extracting the teeth in question. However, you can do something to make sure the teeth that are still ok do not go down the same route and this would be to make sure to are brushing and flossing twice a day and that you are keeping food and drinks with a high concentration of sugar in them, such as sweets and coke, to a minimum.
The smell you are talking about is from the decay in the teeth and it will not go awat until it is removed by a dentist so I would ask around friends and family for a dentist they recommend and book an examination with them.

Kind regards

Dr Justin Glaister
www.umbrellasmiles.com