I am having severe dandruff and hair loss, I am 39...

Dandruff treatment?
Use special shampoos to treat dandruff and keep washing daily to prevent dead cells from accumulating, such as ketokonazole shampoo, selenium sulfide lotion, zinc pyrithione or zinc  madine.
Causes of dandruff?
    Dry scalp skin
    Using some types of shampoos that are not suitable for the skin, causing sensitivity to the skin of the scalp
    Malnutrition and thus the skin lacks many of the nutrients it needs to maintain its moisture
    The age stage where young people are most exposed to dandruff due to more hormonal activity
    Eczema of the scalp skin
    Head fungi
Dandruff prevention:
Washing hair twice a week, not exaggerating the use of hair care products and avoiding exposing the hair to harmful chemicals, especially those in dyes, not exposing the hair to temperature differences, and eating healthy foods rich in omega-3 if the imbalance of fatty acids in the body is the main cause of dandruff.
How is dandruff treatment shampoo used?
    Rinse the hair with lukewarm water before using the shampoo
    Apply shampoo to hair and rub hair gently
    Leave the shampoo on the hair for 5 minutes
    Rinse the hair with lukewarm water again
    The shampoo is used once a day for a month
Advice:
Avoid stress and not use hair-proven products, wash the head with daily shampoo, exposure to sunlight, and follow the previous instructions, and in the event of no improvement, visit a dermatologist.