I Have Had Outer Labia Blood Blisters For Ages. Occasional

I have had outer labia blood blisters for ages. occasional little bleeding, no big deal. 5am this morning felt like I'd wet my pants. didn't. pants, towel and moisture protection pad under me soaked with blood. panicy til discovered it was from blister, not vaginal. it kept bleeding profusely for 1/2 hr or more finally got it slowed enough to get cleaned up, including the floor, and get on clean panties and heavy poise pad. when I arose pad had significant blood but not soaked through. after using the toilet, before I touched anything for clean up, discovered blood in toilet.bleeding profusely again. managed again to get it slowed enough to put on clean pad. what can I do to avoid again? or,what can I do to stem flow if it recurs?