Did not read the comments. I had similar symptoms when my house developed a leak in a pipe inside a wall and started growing odor-less toxic mold (wallemia, in my case.) Doctors had NO CLUE what was happening and I did a myriad of things trying to fix myself before I found out (on the internet of course) what the cause was. It damn near killed me, and did kill both my cats. It could be any toxin you are exposed to, or perhaps you have EHS, or both....for the mold, you can get the very best test there is (better than the "pro" air tests, which don't even look for that particular mold) and it's called the HERTSMI-2. $155, you do it yourself and send it to the lab. mycometrics.com Best of luck and I hope it is that simple.
Wow. This is insane. I was thinking about calling my utility provider to ask them for a test regarding our water - the house is over 100 years old, dilapidated and full of mold. Its crazy that you'd leave this comment when its something I've been thinking about these past few days. Only thing is I'm not sure the HERTSMI-2 test is available in the UK :/