I found this on another website (Recipezaar.com) and this sounded like something I can have. In the nutrition section it said one cookie has 3.5 carbs but it would likely be less if you use Splenda.

PB Cookies
1 cup peanut butter (use PB with no sugar added)
1 cup sugar (use Splenda)
1 egg, slightly beaten
1 teaspoon baking soda

Heat oven to 350 degrees.
Mix peanut butter and sugar until creamy.
Add egg and baking soda. Mix well.
Drop by teaspoonfuls onto ungreased baking sheet, 2" apart.
Dip a fork in sugar and make a criss-cross pattern on the cookies.
Bake until slightly browned, but still soft to the touch, about 10 minutes.
Let cool on cookie sheet for 2 minutes.
Transfer to wire rack until cooled.