Ok so a few weeks ago I developed this clear water fill blister just above my left knee.( Mind you, I have edema in my right leg. Not my left.) The blister eventually drained then developed this 1mm in diameter and maybe like 1/10 of mm deep - sized sore. It looks like someone too like an end of a mechanical pencil eraser and drilled it into my skin and then after hours of doing that this sore developed. Only I wish I could say that happened because then I would know why this blister has caused this. It won’t heal. It develops pus under it but just around the edges. Leaving any time I try to get the infection out it’s not getting worse or any better. It still the same size as it was two weeks ago. Can anyone explain this? I have never had a blister do this and if it did it was on my ankle when I was wearing shoes a lot and it still healed within a few days. Help please. I’m 30 yrs old and female. I do have psoriasis on my scalp and tinea versicolor (not ringworm) on my back.