I think if you cut out only ALL carbs and dairy, you will no longer have rashes...and your digestive issues will simmer down. Just write out a list of possibilites for means and stick to it.
Breakfast: an omelette with cut red pepper in it. Maybe bacon or sausage. Or a smoothie made from almond milk and a few vegetables. I add protein powder myself. It stops cravings.
Lunch: a big salad and cut up hard boiled egg or chicken pieces. Unlimited vegetables can be in the salad.
Dinner: bbq shrimp or steak with a variety of vegetables. Beets, cole slaw, cooked broccoli with butter and garlic, carrots in butter with onion bits, cooked pepper strips and onion in oil.
Whatever you are trying in terms of a diet is probably far from the above because eating 100% healthy and cutting out grains, cereals, sweet foods is a challenge and just not how we normally eat. If we did, we would be much healthier. It is quite resrictive but if you can do it for a week, you will notice the difference.
Milk and therefore all dairy is a very unnatural food for humans. It is the breast milk of another mammal...meant only for calves. Not even an adult cow would drink milk. Cows live on grass. No other mammal drinks the breast milk of another species...except humans.,...and we drink or eat dairy products into adulthood. Very strange...
Because I have IBS, I put acidophilus in my morning smoothies. It's called BioK but may go by another name where you live. They sell it in grocery stores and it is quite expensive but you only have 1 TBSP. I get the soy based kind...not dairy of course. Acidophilus keeps the good flora growing in the gut and elminates the bad flora.
If you do have IBS with painful attacks, it is a sign of constipation. One needs to drink more water, take 2 - 3 magnesium citrate tablets at bedtime and stools will pass easily. The aim is to have healthy, 1 foot long, bulky, easy to pass (3 seconds) stools like Africans who eat a high roughage diet (which we should be eating). Magnesium citrate helps you to achieve that. This helps eliminate waste quickly so that it doesn't fermet and 'rot' inside you causing bloating and discomfort. Maybe that is all you need; to be regular and produce African stools! lol
Good luck!