By the way, I have very dry skin, and I've never had acne.
This could be because of the sun burn which would have been aggravated by the dry skin you have.
You should use a medicated sun screen all the time - preferably one prescribed by your doctor or skin specialist.
You should wash your face several times with a non drying face wash and also refrain from using too many cosmetic products. Drink plenty of water, and wear a hat when going out in the sun, or use an umbrella.
If the lesions still remain after a few days, consult your doctor or skin specialist and get a clinical examination.
Let us know about how you are doing and if you have any other doubts.
Thank you so much for your helpful information. :)