Very swolen, itchy and blotchy
Only appears after 5 day

Not surprising, really. Most people have dirty or sandy feet if they are exposed to direct sunlight. Cool them in a bowl of cool water with a little baking soda, and apply some aloe lotion or Solarcane or any soothing sunburn product, and spray on some cortisone spray for the itching. Take some Benadryl for all of it.