What Causes Puss Filled Blisters On The Face?

I am white 50 yo female and was out on a tractor spraying weed killer over 10 acres in hot sun. Had sunscreen on my face and held my shirt over my nose and mouth at times, trying not to breath the stuff. Very hot day. That evening, my chin broke out into tiny pimples and hurt. Of course each one I popped oozed clear and then pus would reform in an hour. By the morning my chin looked horrible. I used aloe, then Benadryl cream, then cortisone cream, then by the end of that day, used a steroid cream by boyfriend had gotten from his doctor, which has done a lot to help clear it up. These were pin point pus filled blisters that Oozed..what is it?? My chin is red now but blisters are not as bad.