I upped my protein intake from nil to 50grams about 2 years ago (I had anorexia and was "scared" by anything that wasn't fruit or veg) my weight shot up and now I weigh alot more (too much to look on the scales) I eat alot more protein now also.
I have not had any issues with cramping, infact I tended to cramp (do you mean 'stitch' in the abdomen?) a great deal more when I didn't get any protein (unless you wanna count the mini grams of protein in apples and leeks...) I used to find that the cramping would occur if I ate alot/too much too close to exercising. You have to play it by ear, there are times I can stomach a full lunch and go to the gym literally eating as I am getting changed, and other times I just don't seem to be able to workout as well as there is a stitch in the way, its hard to really know which is which unless you really focus hard on how you feel when your eating and learn the hard way. Sometimes you just *know* when your above your comfort limit and wont get as good a work out. Othertimes you know you are able to push it more. It doesn't seem to matter what I eat or what time I eat, my body changes daily.
Things which I think influence cramping (a stitch or abdominal pain whilst exercising) are....
Eating too close to exercising when you are already full- this includes protein shakes or any type of shake, smoothies, diet coke... you need to be able to work your core whilst you exercise, too much food or air inside it will give your core alot of work to push against and I'd think tire you out alot more.
Not resting enough (sleeping I mean) which aids digestion and means you have less in your stomach.
Not drinking enough water or drinking too much drinks which have sodium added. An inbalance of sodium in your body can result in more cramps. Drink plain non fizzy water and wiat for your body to digest the water (20 mins) before trying to knock sevel bells out of your legs on the treadmill!
Electolyte imbalance. Similar to the above. There are drinks that can help or you can make your own with 50:50 fruit juice to plain water and a pinch of salt. Rehydration sachets can also help as can bananas and yogurts.
If your cramping gets in the way of your training, it could be your training too hard. Maybe take it down a knotch (say if your running, knock off 0.5 to 1km/h till you can run 10 mins without pain) keep a diary, watch your improvement and see that things get better (eg keep the speed the same, increase the time until you cramp and see how much longer you can do this for). I'd imagine your cramping is a muscle which is weak for whatever reason so when you run or workout, your using this muscle and training it. This means when you do over work it, give it some time to recover. The going rate seems to be 48 hours. Maybe move onto a different exercise where your abdomen (or wherever it is) does not cramp on the days inbetween if you do feel you need to workout inbetween rest days.