Nicotine Addiction :: Feeling Ill After Quitting Smoking!

I quit smoking exactly 1 week ago today (though it feels much longer) after smoking for almost 7 years. 

For the past month and a half, I have had shortness of breath, which came on suddenly. I went to Urgent Care for it, and the doctor, after listening to me breath/listening to my heart, said "everything sounds good", and she said my shortness of breath is due to the fact that I have severe anxiety/panic disorder and a sinus infection. That was in the beginning of February... A couple weeks ago, my best friend's mom (who has been an ER nurse for over 20 years) listened to me breath, took my pulse/blood pressure, and she, too, said my lungs sounded "perfect", and my other vitals were good as well.
However... here I am, late March, and I still experience shortness of breath (though it has gotten somewhat better). 
Like I said, it's only been a week since I quit smoking (which I did BECAUSE I felt it might be why I was having shortness of breath), and the first couple of days? I felt great!

Now, I feel awful. I feel like I am dying. My depression has gotten much worse, my anxiety is acting up, I feel "empty" both mentally and emotionally... I have HA (health anxiety) and I fear I might have cancer, or COPD, or some such thing. 

Also, physically I just feel completely drained. I feel weak all the time, exhausted, sluggish, my heartbeat feels weak (to me), etc... I have difficulty thinking clearly, my concentration is horrible... 

But mainly what bothers me is how weak I feel... Sometimes I feel so weak that I am SURE I am dying. I lay there and think, "this is it, I am dying". It's absolutely terrifying! 

I use a nicotine patch, and it DOES seem to help when I have it on, but it only helps so much...

Is this all normal? Before I quit this past week, I had been quitting on and off for a couple months, but my "quitting" would only last 2-3 days. This is the longest I have quit smoking.

I just feel something must be terribly wrong with me... Could this all be just because I quit smoking? No one ever tells you what to REALLY expect when you quit...