Hello,
For seborrehic dermatitis on the face, topical steroid creams may be needed. But these are available under prescription. Moreover sudden swelling and itching of the eyelid can be due to allergic reaction or angioedema. An allergic reaction can occur suddenly, even in a person with no previous history of allergy. This swelling is called angioedema Please consult a dermatologist/ allergist soon and get the diagnosis confirmed.
I hope it helps. Take care and regards.