Thank you for your question. Dandruff is a fairly common condition but it can be quite stubborn and persistent at times.
You can try simple over-the-counter shampoos such as Head and Shoulder shampoo and Ketoconazole shampoo which may help to control the dandruff. Tar shampoos may also be helpful.
In persistent cases, topical steroids may be prescribed and they are very effective in controlling the redness and scaling.
If the condition remains severe, we do have to think of other conditions like scalp psoriasis which can present like dandruff but this is often more severe.
You can consider seeing your doctor or dermatologist for further assessment and treatment if your condition remains persistent.