Can inonotus obliquus-chaga mushroom cure my skin disorder(seb.dermatitis.)?

Unlikely: Unfortunately an ailment like seborrheic dermatitis tends to be a chronic inflammatory disorder with limited data in regards to curative treatment. The Chaga mushroom has demonstrable anti-inflammatory properties and has been reported to help conditions like seborrheic dermatitis. Be aware, the data is limited. It's unlikely to harm you in topical form but may provide limited help. Good luck.