Well, generally speaking, there are many people whose eyelashes are falling out. So you do not need to be too worried about it. There are also many reasons which can lead to the falling out. For example, some cosmetic products, such as mascara and eye make-up, can be the allergy to them, and then, it can make your eyelashes fall out. So you should change these cosmetic products. Also, to treat it, you can just stop using them. Maybe you can also use some black seed oil applied on your eyes, in that way, it may reduce the falling out. Anyway, just go and see the doctor.