I'm sorry you are going through all of this! What else have you tried for sleep? Lack of sleep alone can cause horrible symptoms because your body cannot repair itself or function. Whatever you have that is making you sick, your body will be able to fight it much better if you can get sleep each night.
Ambien does nothing to help me sleep, and neither does Tylenol PM or several other prescriptions that my doctor and I tried. Google ativan as a sleep aid. It is the first thing that helped me sleep. My problem is that all my symptoms make me so uncomfortable that i am just restless during the night and usually half awake or completely awake trying to get comfortable and actually fall asleep. Ativan (also known as lorazepam) is a muscle relaxer and anti-anxiety medication. You don't have to have a problem with anxiety for this to be a great solution for sleep. Ativan settles your mind and helps your brain, nerves, and muscles to relax, even despite the symptoms that would otherwise keep you awake.
And forget about the doctors who say you have anxiety....unless YOU think you struggle with anxiety. Keep in mind that it's not shameful to have anxiety. So don't be afraid of that as a diagnosis, but also don't settle for it if you know there is something else going on. It is also possible to have anxiety AND a physical illness....being sick makes most people a little anxious. Especially when you don't know what's making you sick and you don't have insurance. Clearly you are sick, so something needs to be resolved to help you get your life back.
I would start by addressing the sleep issue, and see how that helps your overall condition. Can you call the doctor who prescribed ambien and say its not helping? He may be able to call something else in. If the doctor is not an option, or if you want to try something more natural first, there is a really great herbal supplement that works well for sleep. It actually even works for me. It is called Gaba Ease (mine is made by Vitanica). You might also look into melatonin. I am not sure how that one works, but people swear by it, and you could google it. I would only try one of these ideas at a time, because I don't think they are meant to be combined.
Other things that help with sleep...be out of your bed during the day. Be up as much as you can tolerate, but if you need to rest, rest on a couch or chair or somewhere different from your room. That way your brain will associate your room and bed with sleep. Try heading pads if you have muscle pains, that helps me relax and sleep. I use a sound machine because it also trains my mind...when it hears rolling thunder....time to sleep. It also drowns out other house and neighbor noises, which keeps me in a sound sleep.
Also, as far as helping your body get through this, try to get in some exercise each day. I have been house bound for the better part of six months, and often can barely make it down the stairs....so i understand what I am suggesting when i say to "get in some exercise". But you have to keep your muscles alive and working or you will cause problems that are simply from being inactive. When I forget to take 15 or 30 minutes to work out my muscles or get my heart and breathing rate up, i get more muscle aches, more muscle stiffness, joint pain, painful lungs (this is from the lungs only expanding partway for days or weeks on end), my balance and walking are worse....there are alot of bad side effects that come from just being sick and inactive. So figure out what you can tolerate. Lay on a mat and do simple leg lifts, get 3-5 pound wieghts and lift them in various directions, do some sit ups, walk up and down some stairs...simple, but try to keep your muscles active and get your lungs to expand. This exercise will also help you to be more tired at night so you can sleep better. These are all things I have been taught by doctors and physical therapists in the past six months, and they have really helped me. Not sure how it applies in your situation, but thought I would share.
I'm sorry you are going through all of this and I'm sorry that I don't have any brilliant answers to help with your diagnosis. But there is alot of support here on the forums, so definitely stay connected and let us know how you are! Hope things get better for you soon.