I have the sam problem and yes it sucks!!
I tried using Anti-Dandruff Shampoos like Head and Shoulders and one from Pantene ProV but they didn't work.
But Selsun Blu helped a lot!
I recommend it.
Make sure that after you apply the shampoo and conditioner, you rinse out your hair a lot and make sure that no shampoo remains especially above the neck.
Another tip - don't change shampoos and conditioners too often.
Choose those that work best for you and stick to them.
I always used to use Pantene Pro V and never had any dandruff, then I started using L'Oreal and Herbel Essences and my hair became....****
I think all the different chemicals irritates your scalp sometimes if its sensitive.
Stress also causes dandruff so relax
Hope I helped!