Messy bun makes hair curly but its very frizzy any tips?

soo i wash my hair put some type of frizz Control thing on it and gel to tame it and grab my hair from top till all my hair is clamped in hands and put it in a bun its messy then i sleep on it THEN the problem starts next morning i untie the bun and my hair is stiff and reallllyyy tightly curled with ringlets and i stretch it then by the time im ready to put it down its frizzy looking any tips? i tried putting it under water and the curls stayed in successfully but when i went to styling it started frizzing if i do this everyday will my hair start curling up like this cus when i wash my hair it stays curly and my hairs naturally straight.