What causes & how can i prevent a development of a boil in my body. i have 1 under my lhs underarm, i had another on rhs in 2016 & another 1 in 2014?

Recurrent boils: aren't uncommon, several reasons for that, you want to exclude blood sugar problems, so check your random blood sugar, overweight in itself can be a cause, so try to reduce weight if you are, cut finger nails short, bathe with antiseptic soap, avoid pets, etc.. see your doctor for assessment if above fails or you have abnormally elevated blood sugar, best wishes