If my grandmother is to be believed, it is because you started eating the crusts on bread.
Why has my hair suddenly become curly?
Have you gone through anything drastic lately? (Had a baby? A lot of stress?)
My eye's used to be brown.
Now they are green.
It is probably your body changing. I know when my body started changing (i'm a girl though..) my hair went from sort of wavy to extremely curly with ringlets. I'm not exactly sure why this happens, but you might just have to embrace it.
Curly hair needs a lot of moisture to stay healthy so natural oils are really good for it. But if in your case, your hairs too greasy, i would suggest a mild shampoo, shampoo for oily hair or dry scalp, or even baby shampoo. Also, you can wash oily hair daily, but concentrate the shampoo on the hair away from the scalp to remove the excess oil from the hair, not on the scalp itself, because this can dry the scalp even more. And watch out for soap residue which can make oily hair worse
cutting it short can possibly cause it to become straighter but if it becomes really curly as you said, then really short hair probably isn't for you. I would suggest growing it out some and see how it goes.