Are your flares symmetric or asymmetric? What does it mean if your flares are asymmetric, that is primarily on one side only?

I get flares sometimes in the right foot, sometimes the left foot and sometimes both.

Mine are the same as twinklee, mostly right foot, sometimes adding left foot and right hand. Left hand flared just once.

Does asymmetry or symmetry suggest anything about whether you have primary or secondary?

Mine go both ways. Sometimes bilateral (usually when in feet), sometimes just on one sides (usually when in hands).

I believe studies have indicated that primary EM is more likely to present bilaterially/symmetrically. And secondary is more likely to happen asymmetrically. However, neither of these is set in stone. For example, I have both kinds of flares, and I have secondary EM. If you have asymmetrical flares at all, it is more likely that your EM is secondary to another condition.