If your recipe calls for regular flour, use that. If it calls for self-rising, use that. I haven't seen a recipe for oatmeal cookies that calls for self-rising flour, but then, I tend to disregard recipes that call for self-rising.
That being said, there are several reasons cookies do not "raise". If you are using generic sugar, that could be the problem. Most store brands/generic brands are made with beet sugar instead of cane sugar. Beet sugar will cause cookies to spread. Same thing if you use margarine instead of butter that is called for - and never use whipped butter or margarine.
Also, the temperature in your kitchen can affect your dough.
It also helps if you refrigerate any cookie dough for a brief time before baking.
Over-mixing can cause some cookie batters to spread.
You might want to check your baking powder - it might be old. Add a spoonful to some water. If it foams up, your powder is fine. if it doesn't seem to be very active or simply does nothing - better pitch the container and buy yourself some new baking powder.
Hope this helps