My mom has bruises that came up on her arms & thighs. bruises are very red around the edges; like infection?

she had went to the er; they took her blood and gave her a pain pill and sent her home..now the bruises have blisters coming up; some of the blisters are huge; also her hands are swelling and her whole body is aching. im very worried; what could this be and what should i do??