Welcome to the forums
I'm glad to hear you've made some progress with your symptoms recently. I've also been on a long journey and am slowly finding things that help me.
I can certainly relate to your symptoms and am sure many others can as well. The vast majority of your symptoms are very common in all the 'environmental illnesses' covered on this site and I really empathise with you as what you describe is what I have had most trouble with as well.
One that really set a bell off in my head was you describing feeling worse in crowded stores. This is typical of chronic fatigue syndrome, fibromyalgia and multiple chemical sensitivity/environmental illness. I was diagnosed with the first of these in 1990 and know the 'store fatigue' feeling well. It's thought that this is because the brains of those of us suffering from these conditions can't process information from the senses properly so quickly get overwhelmed by noise and lights etc.....leaving us feeling drained and exhausted. Another possibility is that you have chemical sensitivities which would affect you more in stores where there's lots of people wearing chemical products such as perfume and deodorants as well as chemicals in cleaning products used in the store. Basically there is a lot of chemical air pollution from many sources in stores.
When you say the radiating pain has a focal point in the centre of your chest do you mean it is actually in the centre? Your heart is off to the left. If it is in the centre right below your sternum/breast bone (middle of the ribcage) this means the pain could be coming from the duodenum, the very top part of your small intestine. This can become inflammed if your liver isn't working efficiently as toxins are dumped into the bile....which is then excreted into the duodenum. I say this as this is something I have also experienced. I have an inflammed duodenum due to 'toxic bile' and certain foods things (spicy food, garlic, alcohol) have triggered attacks of pain exactly as you described. It really is a terrible pain that really takes the wind out of me and takes a good while to die down.
When you said dairy foods were giving you a lot of brain symptoms I initially thought it might be due to undigested proteins from dairy foods being absorbed andreaching your brain. These proteins can act like opiate drugs and interfere with brain function (a popular theory for autistic symptoms and something again that I experience myself when eating dairy products as well as wheat.). If meat is causing the same symptoms then there are two other possible causes...food sensitivity or chemical sensitivity to things which are added to meat and dairy products (e.g. antibiotics and growth hormones). Do organic meat and dairy products produce the same symptoms?
If you haven't already I'd recommend you get your gut thoroughly checked out. Find a doctor who will order tests to look for increased intestinal permeability (leaky gut syndrome), digestive function (production of stomach acid and digestive enzymes), and infections with yeast (Candida, bacteria and parasites.) I'd also suggest you have your liver function tested.
Check out the lab tests
page here to read a little more about these tests.
Hope this helps and look forward to hearing from you again.