Hello and thank you for your question.
Most likely you have a condition known as "seborrheic dermatitis". This is a very common condition which is caused by the overgrowth of yeast on your scalp. Yeast is present on everybody's skin but for some reason in some people it grows more.
One of the most important treatments for this condition is to shampoo your scalp everyday. 3 times per week you need to shampoo with a medicated shampoo such as Ketoconazole or Selsun blue shampoo. The other 4 times per week you need to shampoo with Head/Shoulders for dandruff. Since it sounds that your condition is pretty severe, I would recommend switching from Kenalog spray to Clobetasol solution. Clobetasol is also a steroid but it is stronger then Kenalog. Its available by prescription only. You will need to use Clobetasol every day after washing your scalp with medicated shampoos. Make sure to use a very small amount of Clobetasol as it is a very strong steroid. Clobetasol can be used daily for about a month. After your condition improves, you can continue using Clobetasol 2-3x per week (always on the wet scalp, do not wash it off).
If you have a rash which also involves your face, there are 2 creams which can be of benefit. One is a prescription cream called "Ketoconazole" (same as shampoo). You apply that twice daily in the areas of a rash, very small amount, just enough to be rubbed in. Another is Hydrocortisone 1% cream which is available over-the-counter. That can be used once daily by itself or along with Ketoconazole. Hydrocortisone use should be limited on daily basis to no longer then 4 weeks since it is a mild steroid and when used a lot, can thin out your skin.
I hope you find this information helpful. If you need any clarification or have any additional questions, please let me know and I will be glad to assist you further.
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