hello..thanks for your query
Ideally sunscreen should be reapplied every 3-4 hourly for optimum efficacy.
Now, you can apply a mild topical steroid
on the affected areas like Hydrocortisone
for 5-7 days.
A medicated moisturizer should be applied multiple time throughout the day to keep the area hydrated.If you have any itching , you can have anti histamine
tablets.Remember to continue to use the sunscreen even when indoors.
Hope this is helpful,Take care!