Haven't changed my diet at all, but today I used 3 enemas, although poured out the solution and filled with purified water, and had loose stools and cramps in lower abdomen later. Why the cramps?

Stimulating bowel. You are stimulating your bowel with the water. Best not to switch the liquid out, as you will loose the benefit of the enema. 3 at one time may be a lot. All the best.
You need help. Why the enemas? That sort of bowel fixation is dangerous. Seek medical help.