Yes! I have experience! Not quite like the "cyclic" thing to the extreme that you do, but somewhat similar. I'll assume that they've had stool tests.
First, Pedigree is so full of allergens and fillers - that in itself could be causing problems (read about the adult food here:
http://www.dogfoodanalysis.com/dog_f...duct=3&cat=all)
So, first and foremost, I would get them on a good kibble - NON-chicken or beef (for now anyway). Cut out the cooked chicken and beef that you're giving (for now) - chicken and beef are the 2 most highly allergenic meats for dogs - I'm not saying they are allergic, but it would be good to cut them out for now until things settle.
The safest, "cleanest" thing you could add to their kibble is whitefish (tilapia, cod, sole, flounder, whiting etc) and/or salmon. You could do that for 1.5 months or so - see what happens - possibly adding venison, lamb, rabbit etc. later. If it were me, I wouldn't risk adding chicken/beef until 6 mths. of health go by (if at all).
Good kibbles are: Orijen, Innova, Wellness, Evangers, Nature's Variety, California Natural - you'd get these at quality pet food stores, feed stores, or online.
Those intestinal noises you here are what ibs/ibd sounds like - and food allergies can sound like that too. So, if you can get rid of the offending food, you could be in great shape. Welcome to YT and I hope you can find a solution!