I did the 'immunobloodprint 1' test for allergies about 8 months ago and although there is some criticism of it by mainstream medicine, it helped me so much, it's a really good starting point. It's just a blood test, but the drawback is it's quite expensive. I think about 400GBP or so. It tests for a ton of common foods. It came up with 20+ sensitivities for me. What is worth bearing in mind (and what I wasn't made aware of at the time) is that it's possible some of these are false results and also possible it may not pick up some problem foods.
What's great about it is it tests for IgG and IgE allergies. IgG are harder to identify yourself because the reactions are delayed, and can take place up to 72 hrs after you've eated the problem food.
Some, though I suspect not all, mainstream practices offer these kinds of tests. Otherwise naturopaths do.
I really am too lazy to do the pulse measuring thing--I've heard about this too--and just wanted more a 'quick fix'!
What you said about flaxseed.. until all this happened to me I didn't realise either that you could be allergic to things like this.. but apparently you can. It's possible to develop intolerances to anything! I have found pysllium (something often used by people when doing a 'bowel cleanse' to have a bad affect on me. I took it regularly for a few months and I think i developed an intolerance.
Having tried out the mainstream doctors and finding they don't have the answers, I'm now turning to homeopathic/alternative medicine. Like you said these forums are really good for learning from other people.
If you've never had one, I'd also recommend doing a CDSA (which includes an advanced parasitology test). HAve you done one of these? I have done the parasitology part--and that's another whole story, which led me into the last few months of pursuing one theory for my problems, but which unfortunately didn't solve much--but now I'm about to do the whole CDSA. As well as a hair analysis test..
I'm considering doing the B cleanse and the P cleanse as well as the zapper. Have you heard of this? I was so not a believer at the start but having read about so many people's positive experiences, I thought there's no harm in giving it a go..!