lots of diarrhea after laxative- safe to start extended water fast?

So I'm coming off years of heavy junk food addiction that has really messed up my health, especially my digstive health. Monday I started a very pure paleo diet with grass fed beef, vegatbales, and sweet potato. I'm 20, male, 6'3 and normal weight with a little bit of extra fat.

I didn't have a bowel movement for 5 days and starting feeling pain on friday.

So Saturday I had some junk food and a laxative to try and force myself to have a bowel movement, which I did...one big one yesterday afternoon, and then a very "volumous" diarrhea episode this morning.

I know diarrhea can cause electroltye disturbances and dehydration- do you think I'm safe starting a one week fast today? Or should I eat and drink today and take some supplements and start tomorrow?