I had asked for some further information and have not heard back.
There are several considerations with these symptoms.
It is not common for an abscess to present with shortness of breath when lying down. An abscess is possible, but not very likely.
The most common cause of shortness of breath when lying down is from fluid accumulation in the chest, usually from congestive heart failure. However, fluid collection, by itself, typically would not cause a fever. But if there is fluid accumulation for any reason, then a chest x-ray will usually detect the fluid.
If there is drainage in the chest that is worse in certain positions that also can lead to infections, it is more common that it is from bronchiectasis
, rather than an abscess. Bronchiectasis is when certain airways are damaged and larger than normal and can then collect mucus and/or pus. Again, a chest x-ray would be the first test to be done.
If a plain chest x-ray is not sufficient to identify the cause, then the next test would usually be a CT scan of the chest, which would detect the few abscesses that might present with these symptoms, and would be more sensitive than a chest x-ray for bronchiectasis.
If I can provide any further information, please let me know.