Hello and welcome to healthcaremagic
Itchy scaly scalp along with eczema elsewhere on the body could be related.
The first thing that comes to my mind is psoriasis, which commonly affects the scalp and body with itchy scaly erythematous plaques.
I would suggest that you see a
dermatologist for a confirmatory diagnosis.
Treatment would comprise coal tar and
salicylic acid based shampoo along with
topical steroid lotions, calcipotriol lotion etc
For cutaneous lesions topical steroid+salicylic acid based ointments are commonly prescribed. Topical Vit D analogues e,g calcipotriol,
calcipotriene ointments are also useful remedies for psoriasis.
For widespread disease systemic treatments in the form of immunosuppressives like
methotrexate, cyclosporin etc can be started, however for limited disease topical treatment alone would suffice
Regards