What Causes Blister On Stomach That Is Growing In Size?

Hello...I am writing because I have a round blister-like wound that appeared on my stomach about 1 week ago. It appeared when I woke up one morning and I thought it was a bug bite so I applied triple antibiotic on the wound and left it open without it touching my clothes (I was at home that day). In about 4-5 hours I looked down and it had gotten a bit bigger, about the size of a cigarette burn and it was open flesh. Now it has stayed the same size and has healed but it p;eeled on the outer corners and left a little scab right in the middle. The outside of the tiny scab is still pink but it seems to have grown some skin over it. Do you know what this could be? Thank you!