Eczema, what causes it and what are the symptoms?

so i think i may have eczema, its a bit out of the blue, i noticed it when i got out of the shower this morning, its kinda pink/red, and slightly bumpy and flaky skin and its kinda itchy, its been bothering me all day and i have no nails, so i scratched it with the key to my front door, so id just like to know, what are the symptoms, what causes eczema and do you think this sounds like eczema, and what should i do about it?:( its really sore, i've applied moisturizer and sudocrem.