busybeejay, I'm so sorry that you are having to suffer this. However, I am going to sound quite harsh, but you really need to seek help, things are not going to get any better, if you do nothing.
I am in a similar situation as you, even climbing the stairs was well nigh impossible. Unfortunately, I have multiple health conditions, including severe heart and lung conditions, but was reluctant to bother anyone, as I was sheilding.
Also my GP didn't monitor nor even contact me for two years, no bloods etc. were done, so my health deteriorated rapidly. I just couldn't face the dragon receptionists, trying to access help. Consequently, I ended up in Coronary Care, in the height of the pandemic.
I know now that I was extremely foolish and somewhat reckless, in not insisting that I need support.
However, one of my consultants contacted my GP, because he was so concerned about the condition I was in. I had felt quite hopeless and was concerned, I would always be like that.. ?
My GP received letter, subtly making my GP aware of the fact that I had been let down by him. On receipt of the letter, my GP contacted me and is now calling fortnightly.
On a positive note, my medication has now been changed and tweaked three times in the last four weeks and there has been a significant improvement, (that wouldn't be difficult) thank goodness.
I should have told someone, how unwell I was, rather than put up with it, because I thought doctors had enough to contend with.
If we stay under the radar, no-one will know our plight, nor be able to help and support us. I learned that the hard way, I had no quality of life at all until that consultant stepped in.
I know for a fact, that here in Scotland that if you phone 111, because you cannot access a GP, they will contact the GP for you and arrange a consultation, if deemed necessary.
We can offer all the the support possible on here, but we are not doctors, and speculating about the cause of your breathlessness, isn't at all helpful. The only person who can offer a diagnosis is your GP, but he needs to speak to you in the first instance.
PLEASE PHONE YOUR GP OR 111 TODAY and explain how you are feeling. You need to insist on speaking to someone and not be fobbed off..
I'm sending you my very best wishes and I hope you can access the help you so badly need. ?