Suggest Remedy For Blisters

My 5 yr old nephew spilled a hot tv dinner on his artm Thursday evening. the blister popped immediately. My sister called an after care service and they told her to put neosporin on it, cover and bring him in the next morning. She did and the dr treated and dressed it. This afternoon it has started oozing a green liquid, not hurting more, no temp, redness not getting larger, but concerned about the green color. Should he be taken to the emergency room?