While im no doctor K9, having just answered you other post regarding rest, reading this makes me wonder..
I had pneumonia and pleurisy that started Xmas 2012. I didnt realise i had it till i went to hospital in May. Terrific night sweats, absolutely drenched, lethargy, tiredness to the point i could hardly stay awake at work...and yet i only lost one day at work because of it. FFwd into May/June, antibiotics, bronchioscopy, fluid taken off lung etc etc...FFwd to now, although i still have a niggling cough, i still have a restriction in my ribcage, the leftover from the Pleurisy.
The complications can be severe, pleurisy is often associated with and a complication of pneumonia, and has long lasting effects in my case, perhaps permanent.
That in mind, if you're still being treated for WP...i'd give that EVERY chance to do its magic and not worry too much right now about increasing fitness etc.
JMO...with the thought that i wouldnt stop cycling all together, but let the WP get itself sorted before stressing your body getting fitter.