I suggest you get a physical to see what may be the cause of the flu like symptoms. If all is well with your physical health I would speak with a psychiatrist to get to the reason behind the anxiety attacks.
Aw man, depression is the worst. Been there...
I know the feeling, and not everyone does, unless you've experienced it.
You may already have a great diet but:
One thing that really helped me was a diet change. I went on a low-carb diet just to loose a little weight (cut out candy and bread mostly), and in like two days, I felt %100 better, I was walking around in a fog, and having muscle aches etc, I was eating candy expecting to get an energy boost, but it had exactly the opposite effect.
I still drink my morning coffee with flavored creamer, and carbs in fruits/veggies are always ok.. (try frozen grapes they're awesome)... But avoid most pasta, whitebread, and sugary snacks.
I feel much better. I still get the blues but handle them much better, and I'm much less stressed with work, etc.
(I'll say a prayer for you, I nearly teared up thinking reading what you had going on)...
I think this does sound like depression, plus stress. When stress is added it can make symptoms worse. Maybe something for the stress might help. It does take time for an antidepressant to reach a good level to start feeling the benefits of it. Also, there are combinations that can be used together to boost the other's affects. I believe like Cymbalta is one that's added to take along with another antidepressants. My daughter was at the lowest point possible (admitted to suicidal thoughts), with medication & weekly therapy she turned around. It took a little time, but that's what it takes...time. Hang in there. Also, do some research, things like Hypothyroidism cause fatigue, muscle cramps & aches plus depression.
I don't know your details but my personal experience is that after seeing the Dr and bloodwork came out OK. It was stress for me... and yes it can feel like the flu. I remember having to pull over one time because I was so tired.
After some time my situation changed and finances were better , I stopped waking up in the middle of the night with worry and then I started to feel better physically.
Not sure if this is related but I thought I would share.