Scalp redness, in which builds up of dead skin that feels like small bumps. tried eczema shampoos and seborrhoeic dermatitis shampoos. is it dryscalp?

Its NOT eczema: I think you have PSORIASIS from the way you describe your scalp. See a Dermatologist for an accurate diagnosis since the treatment is different. In the meantime you can try SELSUN Shampoo (OTC) Be Well

Likely psoriasis or: seborrheic dermatitis. See a dermatologist for further management if over the counter shampoos have not had any benefit.