I need to know what's wrong!

I am in a bind. For the loast 18 months I have been unable to work due to physical issues, loss of balancing, periodic brief sudden loss of consciousness, severe fatigue, scratchy eyes and sore muscles. My doctor has been trying to diagnose the problem, but the simple fixes haven't worked. We are a 1 income family, and on my wife's customer service salary it isn't much. Her schedule changes every week, so she can't even get a 2nd job. The problem is that I can't qualify for SSDI without a diagnosis confirming disability. And without diagnostic testing, my doctor can't make a diagnosis. I have insurance under the ACA, but we cannot afford the out of pocket and co-pays for the needed diagnostic testing. Without the diagnosis, I can't get better, and I can't qualify for SSDI. I just want to feel better and be able to leave the house again! Thanks for any support you can give to us in this, thanks so much.