There are many different diseases that can cause skin redness, swelling and pain, and there are three main types: firstly, infectious skin diseases due to local bacterial, viral, fungal or other pathogenic microbial infections; secondly, allergic dermatitis due to allergic inflammatory reactions caused by skin contact with some allergens; thirdly, some connective tissue diseases such as rheumatoid arthritis and dermatomyositis can cause skin redness, swelling and pain.