What Causes Shortness Of Breath While Sleeping?

Hello! I have a big troubles. Everything started 10 years ago, when I was diagnosed with cancer, but lucky or unlucky, it was just a hernia. A year later, I started having problems like waking up in the middle of the night, cant breathe etc. Just an easy problems. After time, the things went wrong. I was affraid to go to a doctor, because I don't want to hear, that I am sick of Cancer. That is still the good part. Few Years later, I started having more serious problems. Currently, almost everyday at anytime I am in a different moods. Once I am happy, everything is fine, next minute I am depressed, and nothing is valuable to me. It happens after I lost one girlfriend though. But the problems are:
1. Cant focus on almost nothing
2. Brain Fatigue
3. Sleeping more then 8 hours and wake up tired.
4. Always thinking of something in the past, cant concentrate
on the present.
5. Social Phobia - recently I found , that I am having it
6. Hard time to organize my day. When I sleep less, like 4 hours
I am feeling more organized and easy going. But on the next day,
I need to sleep more , like 10 hours and when I wake up, I am confused, stressed, tired, and the day is just passing by me.
7. Sometimes, I am feeling, like I am out of my body and my life is just passing near myself.
8. Avoiding reading documents and doing work, where brain is involved more then normal. That 's a big problem, because the
quality of my life is getting worse and worse. Currently, I am 30 years old, finished my law school, but don't want to tell you how
hard I took my exams, because, when I read something, I do forget it very fast
9. It is hard for me to remember many things from my day. Everyday, I am not having many memories. For Example,
not sure what I ate, not sure what movie I watched, not sure with whom and when I have a meeting. Cant organize myself, and the biggest problem ever is, that when I have all those symphoms,
I start stearing in the mirrow and I see, that somehow, my eye
is changed. The way my eyes looks is a bit scary even for me. When I dont feel this pressure in my eye, they seems well, but often they skin where my eyelash is located is purple to red colour. this is only on one of my eye.
10. Tired during the day. Need a sleep often in the early afternoon for at least 30 mins.
11. Cant focus on many things, even if I want to.
I would like to ask you, please, give me a clue, because when I go to doctor, everyone says, that I am ok, and this is just a depression. It is not, I am sure. I read forums, about Bipoliar Disorder, Concentration Disorder, and almost every desiase, I have the sympthoms. I need to know, what I am seek of, so I can take the propper treatment and have at least more normal life.
Thank you very much , and hope to read from you!!!