It's kind of obvious, I got a weird pneumonia, and even when interspersing walking for and hour or more I'm starting to feel my back muscles getting sore just f

It's kind of obvious, I got a weird pneumonia, and even when interspersing walking for and hour or more I'm starting to feel my back muscles getting sore just from lying in a bed and sitting for most of the day. This has been just over two weeks. And the weather is now cold so I cannot take longer walks. (On the other hand, diet is even more adjusted so I lost weight rapidly.)