I have a sore, crusted and scally scalp that frequently oozes and my scalp is very red and extremely tight and sore?

It oozes a clear liquid, right?  If so, you likely have a form of dematitus.  Mine itches like crazy sometimes, and I seem to get some relief from the itching by dumping Sea Breeze astringent on it.  However, you need medication.  You will either need to be treated for a yeast-based problem (yeast is over-producing in your hair follicals, and/ or you need a topical steroid to get the irritation under control. 

I have found Capex shampoo to provide the most effective relief.  Twice a week during the worse months of the year seems to keep it under control once it is controlled.  Make sure your hair and scalp are dry before going to bed... that makes a huge difference for me.