Went to er last Tuesday with knot on calf of leg. They did ultrasound and said there was nothing to drain. Doc perscribed antibiotic for cellititus. Now there is a new knot coming up under other one. Today blisters formed and the pus and blood mix drained out. Leg is still very painful and redness is still there. Pain seems worse now than before. I've been taking antibiotics as perscribed but I am also diabetic. Should I go back to er?

Yes, please go back to the ER.