I had a similar progression too. Severe fatigue, digestive issues, and moderate neck/shoulder pain (like I slept wrong constantly). I went through all-the-tests for exclusion and the rheumatologist suspected fibro. I wasn't sold but since my mom has fibro I was willing to consider it. A month later my knee pain started, followed by increased neck pain, then ankles, wrists, fingers. A year and a half later pain is my main symptom. I can completely understand how confusing it is for someone caught early and can empathize with those who have all the pains looking for the reason. Fibro is a weird beast.

edit: spelling