Hi, KKitty. I have chronic pain and chronic illness too. I've done a couple Whole30s and a lot of "Whole-30-ish" long-term eating. Though I do some coaching, it is not health coaching, so please don't take my post as professional nutrition advice!
That said: if the Whole30 helped you notice nightshades, that's a great thing. If I were in your position, I'd turn this into a Whole60 or at least a Whole45, and eliminate the nightshades, too. Shannon suggests something similar. Then do the reintroductions—slowly, and not starting with nightshades. Reintroduce lentils, wait three days, etc. Do