What Causes Blisters On Shoulder Oozing Yellow Pus?

Hello reader, I was at a beach this weekend (as you do) and forgot to rub sunscreen on my shoulders (as I had a top on at the time) and it got pretty badly burned. (3-4 hours of heat/sun) Blisters started to appear on the monday (2 days ago) but.. Last night/this morning, small amounts of yellow semi-transparent liquid is oozing out of my shoulders. I m not sure if I should be worried or not. I ve been applying aloe vera after sun Gel on my sunburned areas for the last few days and keeping myself hydrated. What should I do? Thanks