Hello, The rashes, fever and swelling on face, hands, joint pain can be due to some viral or bacterial cause likely. Although the malaria and dengue came negative. Chances of other viral infections cannot be denied.Other reason can be allergy to some substance. I suggest you visit your physician without further delay as the appearance of rash should be examined properly. Also as the swelling is on face, toes few blood tests need to be performed to see how the vital organs are functioning as well as the underlying cause of your symptoms. Once the cause is clear, further appropriate management will be suggested by the doctor. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Manisha Auradkar, General & Family Physician