What Is The Blood Filled Blister On My Stomach?

I have a pinch bruise on my lower left stomach area it started bleeding out of nowhere and sort of looks like a blood blister or possibly a bite. I dont recall hurting myself and didnt even know it was there until right before it was bleading. my husband said he noticed it when i was in the tub but assumed I knew it was there. I cut hair at a nursing home and there has been a case of staff there that I am aware of. I had gullbladder surgery the first part of October. what could this be?