You may be having a condition called alopecia areata, if there are well defined patches of hair loss. Other diagnosis may also be possible and can be ascertained while consulting. However, this is the diagnosis most of the times. Treatment is simple and has different approaches. You need to discuss with a dermatologist to understand it at length. Skin is the mirror of internal health and to get a perfect skin you need to treat both ways - internally and externally. A healthy diet and lifestyle is mandatory to achieve results.