I found out recently the noun 'migraine' can be countable. So it basically means I can count migraines like two or three migraines, but I don't know what is the point to count migraines. Isn't 'migraine' supposed to describe a state not a countable thing?
One may say, "I had not just one, but two migraines today." Here's an example of "migraines" used by a fairly well-regarded website: https://www.webmd.com/migraines-headaches/guide/tyramine-and-migraines#1
A migraine is a condition, like a cold ("I've had three colds this winter!"), an infection, or pneumonia. It is interesting that one can have two migraines, two colds (just not two of either condition at the same time), or two infections (which you can have two of at once) but you may not have "two pneumonias". One may have suffered from two bouts of pneumonia, or two cases of pneumonia, but not from two 'pneumonias'.