Maybe he was under some kind of stress at that time , you never know with young kids. But it's good that it's resolved now. The enlarged lymph nodes , in my opinion , need to be investigated, most probably it's due to a viral or bacterial infection, and there's no harm in repeating tests so if antibiotics are needed , they can be given at the right time.
Nope, same deal, no mention of keeping a diary. I was essentially told that he'd probably grow out of it, not to worry if he wasnt losing weight. Based on your matrix, I would define it as mild now. He recovers fast and the issues were really confined to early/mid 2022.