Hi AquaGuy. I also strongly suspect myself to have ADHD, and am just starting the process of potentially being diagnosed.

I think Adult ADHD is one of the more important conditions to get treatment for if it's interfering enough, just because it runs completely counterbalance to what is expected of an adult in the western world.

So yes, certainly get tested. Thankfully, medication alone seems to be substantially effective for treating symptoms, unlike many other mental conditions.

I suppose you could tell them about the possibility of undiagnosed ADHD, but I'd probably do so with reference to the plans of being tested. This way, it will be more likely perceived as serious rather than merely an excuse. Of course, you could just wait until you are diagnosed (if it is indeed ADHD) but as another post mentions, it's a lengthy process.

If things continue as they have in the workplace and it's getting overwhelming, then yes, I don't see the harm in mentioning something. But really, a warehouse (especially with forklift trucks) doesn't seem like a great place for an ADHDer in the first place!