Extremely Oily Hair

If you are using clarifying shampoo every time you wash, that may be why you are having this problem.  Clarifying shampoos are for stripping the hair of buildup, such as silicones from heavy conditioners, buildup from hair products like gels or sprays and such, etc.  This is great to do for your hair once in awhile, but not that often (I do it once every 2 weeks to once a month).  Using such a drying shampoo every time you wash can make your scalp overcompensate by producing more oil to counter all of this dryness. 

Try using regular shampoo and dilute it with water anywhere from half and half to three quarters water (you can experiment with the shampoo you get see what still gives you lots of suds and cleans your hair, but isn't so terribly concentrated and drying).  Using this more dilute shampoo will help your scalp to readjust and stop making so much oil.  After awhile of using this, you may even be able to get your scalp to adjust to washing every other day sometime down the road.

Tips for diluting:
Mix a one-day serving of it in another small bottle, don't dilute the whole bottle of shampoo at once to help prevent growth of things the preservatives in the shampoo would otherwise ward off (probably not a huge concern, it is soap after all, but better safe than sorry).
Roll slowly to mix, don't shake it.