Painful lumps, also known as welts, are raised, swollen areas of skin that can be caused by a variety of conditions. They are often itchy and can be very uncomfortable. Welts can be caused by insect bites, allergic reactions, or even infections. In some cases, they may be a sign of a more serious underlying condition. Treatment for welts depends on the cause, but may include topical creams, antihistamines, or antibiotics.