What are the autoimmune disease that causes baldness spots at the age of 29?what are the other symptoms needed to rule out the causes?

Alopecia areata (AA): AA is an autoimmune destruction of hair follicles in a patchy distribution in the scalp. See a dermatologist.

Bald spots: The most common condition is alopecia areata which has an autoimmune component. Interestingly, celiac disease can be connected to this disorder. Gluten sensitivity has increased 4 fold over the last 50 years and can manifest in a lot of ways. Try a gluten free diet for 3 months and it may help.

Lumpy or flat?: If you have areas of hair loss with lumpy areas (or scar like tissue) in the region of hair loss, you may have an autoimmune skin condition called "discoid lupus" (DL) which is NOT SYSTEMIC LUPUS. If the bald areas are well circumscribed and flat, it may be alopecia areata (AA - several causes). They are treated differently. A Dermatologist can clarify what you have and how to treat.