5 days after MC HELLPPPPP

i was on Master-Cleanse for 15 days, i lost 14 lbs, now after 5 days off the Master-Cleanse i gained the 14 lbs back plus 1.5 more, im using again my old clothes.im not overeating at all.
I went to the doctor and he told me that my body was on starving mode ( MC)for 15 days, so now my body is trying to compansate for those days, and is storing all the calories. he said that is normal, some bodies react like that while others dont.
whats going on????????? what can i do????????? hellppppp me plz
I tryied to explained him that is too weird that im gained all the weight back so fast, its not normal,but he just told me, eat healthy , exercise a lot, drink water and no more MC.