I'm 25 and all my back teeth are rotten or rotting, can't afford a dentist. is there anything i can do

You can not reverse the loss, but can surely prevent further decay -

1. To prevent tooth decay brush your teeth with a fluoride containing tooth paste. Also maintain good oral hygiene by brushing at least twice daily, once in the morning and once before going to bed. Wash your mouth after you have any food, simply tap water gargle is also fine.
2. Avoid sweets or sticky candies in-between meals.
3. Avoid eating food stuffs with extreme cold or hot temperatures.

Before the condition worsens visit an affordable dentist if possible.

answered by S P