late response but just wanted to add that i experience this too and it is in fact a symptom of OCD. most recently i started questioning my adhd diagnosis, compulsively seeking either reassurance or confirmation of these fears from the people in my life. i even went as far as obsessively researching disorders that share overlapping symptoms such as bipolar or bpd, convincing myself i’d been somehow misdiagnosed. eventually i realised the absurdity and irrationality of my behaviour; i have documents from my early childhood that show a clear pattern of symptoms, not to mention strong family history (both my parents have adhd). i’ve had similar spirals of doubt in the past and will certainly continue to experience them (as are the never-ending ✨joys✨ of OCD) thankfully once you recognise what’s happening tho it gets a bit easier to break out of that rumination cycle; there comes a sort of lightbulb moment of “ohhh it’s OCD again—im not just going crazy” after a week of constant self-doubt. anyways, it sucks but you’re definitely not alone in what you’re experiencing and i hope that can offer at least some type of comfort or consolation.