Severe dandruff. Test would be helpful.

I had dandruff 2 years ago that was not normal. The flakes became visible the next day after shower and I could practically make dandruff flakes rain on something or somebody by (I don't know how to make this clear) by running my hand vigorously on my scalp. I hope you understand that. And now its back for about 6 months. I just tried to collect dandruff flakes on my lap by doing the vigorous shake thing and this was the result. And this not a joke or something https://goo.gl/photos/mUDoooWz6PqkNqMT9 Then I somehow managed to collect it on a table and this is the quantity of flakes I shook off my scalp. https://goo.gl/photos/Py1RKgzfUMeJucR77 I have tried many shampoos from dove that nourishes to head and shoulder which is an anti dandruff. I even bought an anti dandruff from a pharmacy but that shampoo leaves my hair very dry and they look unhealthy and I discontinued its usage about 2-3 washes later. Any kind of advice from home remidies to medical test would be helpful. Thanks