Muscle pain in ribs - was diagnosed with lung cancer at the end of last year. Has anyone else experienced this?

Hello, I was diagnosed with lung cancer in December of 2025 and thanks to a drug named osmertinib a targeting drug I have lived well duriing my time time since then.  But in the last few days I have experiienced muscle pain in the back and lower ribs and found it difficult to move around and cope.  Has anyone experienced the same symptons?