LONG - how to deal when you really become sick? (respiratory issues, previous illness)

I started obsessing about my health and the health of my loved ones when I was four years old.  We had loads of books, including medical encyclopedias and dictionaries, and I've always read too much for my own good when it comes to this stuff.

I had a life threatening illness called ARDS a little over ten years ago.  I was in my twenties!  Years of worrying and freaking out and I genuinely almost died.  My lungs basically got overwhelmed by either pneumonia or who knows what.  It was quick once I got treatment - I literally watched my oxygen sink in the hospital, going from one type of oxygen supplementation to finally being intubated. It didn't help that I had been sick a while and finally gone to an urgent care a few days before, being labeled with bronchitis and sent on my way with a zpack and inhaler, only to be taken away from my home by ambulance.

I came out of a coma, anxiety ridden and concerned, but I got therapy, improved my physical health, and dramatically turned my life around.  I had periods of health anxiety, but I no longer felt as frightened of death.   That started changing again this year when I somehow acquired a very small pneumonia infiltrate that quickly went away.  I felt crazy and miserable.  All of the effects of the therapy I'd received and the sanity I've had evaporated.

And now?  Ten months later... and I'm sick again.  It's definitely not the same as what happened ten years ago, but the symptoms are similar in lesser ways.  They say I have bronchitis, but that was also my diagnosis before I almost died.  I have been in constant freak out mode.  I can't handle myself.  I monitor my oxygen levels, my temperature, and pulse with equipment I have purchased.  If I check my oxygen, do breathing treatments, freak out, and wait.. horrified of my o2 suddenly dropping like it did with ARDS.  Two legitimate ER visits and a visit to my doctor and now I just sit and wait.. Feeling tortured and tormented, trying not to check my oxygen, trying not to Google my symptoms, trying to take my medication and do support care, waiting, waiting.

How do I not go insane?  I mean, I feel like I'm already crazy at this point.  I feel in a near state of panic.  I've stopped taking my cough medicine because I'm afraid it will slow my breathing and screw up my oxygen.  I take everything else, but I'm exhausted.  Walking around tires me out.  I know 88-95 oxygen isn't optimal and I'm so tired.  I wake up with horrible anxiety. I have lots of legit pain and discomfort, but combined.. wow.

How can I just chill out until I (hopefully) improve?  How do I know when to go to the doctor AGAIN?  What does this mean for the recovery I'd made in my mental health?  I still go to my therapist twice a month, so how can I possibly get so crazy so quickly?

I'm just driving myself nuts.  I don't usually post on Reddit, but I feel like I'm emotionally drowning in anxiety.