It sounds like you may be experiencing photosensitivity or a heat-related skin reaction. To prevent this, apply a broad-spectrum, mineral sunscreen containing zinc oxide or titanium dioxide (SPF 30+) daily. Wear protective clothing and limit sun exposure during peak hours. To manage active redness and swelling, apply a cool compress and use a mild, over-the-counter topical hydrocortisone cream (1%) to reduce inflammation. An oral antihistamine, such as cetirizine or loratadine, can also help soothe itching and swelling. Moisturize with plain aloe vera or calamine. If your symptoms persist, please consult a dermatologist for a tailored treatment plan.