Sun tan is a common situation in our country. A span of 3 days is sufficient to cause such issues, however it resolves fast as well. Dandruff is another problem ,more so if you are using hair oils. So consider discontinuation of oils and using an antifungal shampoo everyday for first week and then reduce the application to twice a week for maintenance. You should keep the shampoo at-least for 5 minutes on the scalp for it to act. This should solve your problem. However if problem persists, consult a Dermatologist for proper diagnosis and treatment and to rule out any other skin condition. Hope it helps you.