I am really concerned that your child is suffering from swelling in right elbow. From the description you give it looks like hemangioma
is not dark red in color. Hemangiomas are caused by abnormal blood vessels under skin. They may increase in size during initial 6-12 mths but later they shrink and regress by 7 years of age.
Its not an emergency but it need to be shown atleast once to a good doctor. If doctor confirms it to be hemangioma, then you need not worry its going to be alright. Take care.
Dr Balaji Chinnasami