Getting accommodations in college without diagnosis

I'm starting another semester soon, and I was wondering how I could get accommodations in university without a diagnosis? I don't fit the formal criteria for disability, but I have some conditions that, when I'm symptomatic (multiple times a day), can be disabling. I'm still not certain as to what I have, but I suspect Roemheld's Syndrome, which causes me frequent daily flare-ups of chest discomfort, tightness, tachycardia, vertigo, adrenaline dumps, etc., and I think I might have some form of dysautonomia also, maybe. I have formal diagnoses for mental health (anxiety, severe depression, and OCD), but I don't think those would provide me the accommodations I need for my physical problems. Because I don't have a diagnosis yet as I'm cycling through a number of specialists trying to figure out what's wrong with me, I have nothing to show, and I doubt even with a diagnosis I would qualify as disabled. For that reason, I don't know if contacting the disability department would do anything or if I should instead opt to contacting my professors directly, some of which I've known for some time and I have an amicable relationship with.

I would really appreciate any guidance as this is all new to me and I don't want to go through another hellish semester while being chronically unwell. :")

Edit: I'm located in Florida, sorry I forgot to mention that.