My 21 years old brother has been plagued with this for two years now.
After a trip to Brazil, his stomach capsized. Heavy pains, body entirely devoid of energy, headaches, frequent puking every other night.
Since then, he's visited the hospital several times, had almost all tests done on him, taken antibiotics, gone to a kinesiologist who said it was a parasite that has put the body out of balance, spent over half a year taking the nutritional pills he suggested and he still breaks down with intense pain every now and then.
So the usual things a hospital would check haven't yielded any results (he has been told time and time again that there is nothing wrong with him - the pain speaks to the contrary.)
So every other day, he's knocked out because he's too tired to do anything and when put under stress (10 minutes of riding a gocart), he yet again felt his entire body shaking and hurting for over an hour and now the next day he's all worn down again.
We live in Sweden, so we've been consulting Swedish websites as best as we can, but haven't gone to the English part of the internet until now.
I realize I'm a bit lacking in details, but I'm not the one who has been looking at all the papers and fixing all the appointments.
I will get back to you with a much more detailed list of what we have tested for.
All we can guess is that it is something very rare, since no hospital in this country seems to be able to identify it. That, or we've had horrible luck with Doctors (quite possibly both.)
Please, any ideas or thoughts or suggestions or hunches or absolutely anything would be greatly appreciated.
He's lost over a year of his life already. If there's a tiny little chance that we can find the cause, then no advice is bad advice.
Edit: I can't believe I forgot to clarify this: He has pains all the time. Non-stop. Never ends. It can calm down to an extent where he can at least appear as if he is unaffected, but it's always there. The irregular breakdowns that can happen at any time are that the pains increase to extreme levels again for anywhere from an hour to a full day.