How to get rid of SUNBURN?! please help!?

Leave the blister on your nose alone. Sunburn is still a burn and has to be treated like any other burn. You need a much higher SPF than 15. It will go away or break open and could scar your nose but I wouldn't worry too much about that. Leave it alone or it will scar! It will probably hurt worse in the next few days. You could try a cool vinegar and water bath to help with the discomfort.