I am sorry to hear of your pains and discomforts post fast.
My own thoughts on this are that the use of fruit juices have always been considered to be the gentlest and safest way to break a fast, (especially if hunger has not returned), by using orange juice, or a mixture of orange and apple juice.
Interesting to note how you switched from Watermelon to oranges which seemed to have helped you alleviate your discomforts.
After an extended fast, and without the return of natural hunger, your body has to be very gently kick-started into re-feeding, where nourishment should be reintroduced very slowly by chewing the juice and taking sips over a period of time. Start with small quantities initially, and increasing the frequency and amounts over the period of a couple of days, before introducing whole juicy fruits. This would not apply nearly as strictly with the return of natural hunger, where the body is extremely receptive to receiving nourishment, and where the tendency can be to overeat with what can be a voracious desire for food. "Control" would be then be the name of the game.
Personally I would never break an extended fast on anything but juices, freshly squeezed or straight from the juice extractor; this was the experience of Shelton and many others within Natural Hygiene from the very beginnings of the movement.
I just cannot emphasize just how important the proper breaking of a fast is, whether hunger has returned or not, where nourishment is dealt with in different ways by the body. If not strictly adhered to, this can lead to abdominal discomforts and other problems. Upton Sinclair (the novelist) broke one of his extended fasts (without the return of hunger) on "a thoroughly ripe persimmon, which doubled me up on the most alarming cramps imaginable".