Scaly flaking skin. Has increased.

I have been suffering from flaking and scaly skin mainly in my scalp area since a very long time (many years). Despite taking medicine I have only gotten temporary relief. No permanent solution so far. Before I used to have it even in my underarms and even a band of it on my neck but now its not there anymore. Currently, I have scaly spots behind my ears on the scalp area, and two other spots on the scalp one at the back and one above the forhead and in the groin area.  Pulling off the flaky itchy skin causes oozing of fluid that is slightly sticky in consistency. Two years back I have noticed that my nail bed of the big toe has gotten detached from the nail as it has become dry and scaly as well. I have been using coal tar shampoo and gotten the flakyness to reduce but have not gotten rid of it completely. Recently I have not been able to give time to taking care and hence the flakyness has increased.