There are certain natural ways to prevent bruxism like:
Massaging the temple region
listening to music
Professional methods to treat tooth grinding include
Mouth guard or night guard that you should wear the time when you fell that the problem is at max like you said while paiting.
for the teeth that have already damaged, you should visit a dentist and get the problem fixed ASAP....
More info regarding bruxism and its treatment you can visit...http://www.identalhub.com/article_diagnosing-and-curing-bruxism-13.aspx