"Chunks of hair falling out" is a condition known as alopecia. It refers to the loss of hair in patches or clumps, often leaving bald spots or thinning hair. Alopecia can affect people of all ages and genders, and it can be caused by a variety of factors, including hormonal changes, medical conditions, and certain medications.
Alopecia areata is an autoimmune disorder that causes hair loss in round or oval patches on the scalp. It is the most common type of alopecia, affecting about 2% of the population. Alopecia areata is thought to be caused by a combination of genetic and environmental factors.