There are 39 conditions associated with excessive sweating and skin rash. The links below will provide you with more detailed information on these medical conditions from the WebMD Symptom Checker and help provide a better understanding of causes and treatment of these related conditions.
Sunburn is often associated with a rash that begins as a small, pink patch on the skin or a mole-like spot than then start spreading out. The rash appear within 12 to 24 hours after exposure to UV rays and can be particularly worse if you are under certain medications such as Doxycycline.
On more than one occasion my skin was affected by serious sunburns. I had fever and I was in a lot of pain, but I have never experienced swelling due to sunburn. But, a thing like this can happen in the hardest sunburn cases. You see ultraviolet lights that cause sunburns actually hurt our skin cells. Our immune system sees this as a threat and reacts. The swelling is one of the signs of inflammation. The mechanism of this immune system reaction is very complex.