In the last 13 years prior to going rawpalaeo, I would get massive, very painful stomach-aches every so often. After years of switching diets to raw vegan/fruitarian/sproutarian , I finally discovered that these pains only occured after I ate any cooked animal food. When I, as a last resort, switched to a RVAF diet and started eating raw animal foods, I duly found that I did not get those pains from eating such. Also, most of my other health-problems disappeared within a 4 month period(though, admittedly, most RVAFers facing serious health-problems generally take 2-3 years of eating RVAF diets before they fully recover). I did have to adjust by aging the meats a few days at first so as to tenderise them before eating, as my teeth were on the verge of falling out after so many years of ill-health.
On reading info online, I got the impression that an inability to eat(cooked) animal food had to do with a burnt-out adrenal gland. However, I have no idea as I at the time had so many different health-problems all over my body due to mass inflammation caused by a delayed-action dairy allergy, so it could have had multiple causes.
Everyone is different, so do not necessarily assume that your experience will be the same as mine.If you are overweight, I would recommend water-fasting for 10 days or so at first. Some RVAFers like to do 20 days before going RVAF, but that is a bit much for someone new to fasting.
I too experienced a brain-boost when doing my all-raw-animal-food experiments, but I was terrified to find out, after c. 3 weeks, that a lot of my past health-problems pre-RVAF diet were starting to reappear. I really wouldn't recommend it, since you already have issues with the all-cooked-animal-food diet. You might consider trying "high-meat" every so often as that also gives a brain-boost.
It might be an idea to do 95% raw veg/raw fruit/raw sprouts(preferably organic), and only 5% raw meats, at first. Make sure the raw meat is of high quality(ie 100% grassfed or raw wildcaught seafood or raw wild game). You can always increase the amount of raw meats as you get used to it all. In case your problem is specifically the digestion of meats in general, as opposed to just cooked meats, it might be a really good idea to age your raw animal foods for a few days, or even switch to eating lots of "high-meat". You see, all the extra bacteria in the aged raw meat help to predigest the meat, allowing your digestive system to make far less effort in digesting the meats.