What Causes Itchy Palms And Feet ?

On my way home from work today, I suddenly got incredibly itchy palms and feet. I got home and was almost tearful because of how incredibly uncomfortable it was, quickly getting in the shower to see if some cool water would help - it didn't. Within 15 minutes, my whole body was driving me crazy, with me using a stiff hairbrush to scratch at my skin. It hurts to walk on my swollen feet (not massively swollen, but definitely very hard and tender). Soon after, my bottom lip and ears swelled up and now my voice is raspy and my throat is a little dry and feels a little constricted. I am breathing fine and over the last hour the itching has largely subsided but the tenderness and swelling remains. I haven't eaten, drank or done anything different today and don't believe I was stung or bitten.