I have a really bad sunburn on my chest and it has blisteted and peeled very quickly and im still in pain. is it likely to scar?

Unlikey: The second degree bur you are describing can scar but it is unlikely/. It is more likely that you will have some skin discoloration for a while but that should resolve as well. Its important to keep that cool , and out of the sun. If you can tolerate advil or motrin you may take that for the pain but see a doctor is it becomes tender or a fever begins