Eddie says that he was freaking out in regards to Ana because they “became a ready made family” and he wasn’t ready. And maybe that was true + ptsd + unresolved Shannon grief. It could have also been that in 4x14, he subconciously had already created a ready made family with the reveal of the will

i don't think it was unresolved grief or guilt over shannon—he'd already worked through that in s4, and was even able to talk about her in a casual way at the end of it like he wasn't able to before. shannon doesn't come up at all in s5, so i doubt it had anything to do with her.

i do agree that his relationship with ana was the catalyst, and the underlying cause was his PTSD, etc. though! i think that's fairly obvious and we're not actually supposed to take eddie at his word when he insists that the panic attacks had nothing to do with his trauma...though the point flew completely over the heads of most of the fandom. and we DO see him be contradicted in other scenes (the emergency at air traffic control; the hospital fire). it's only by the mid-season finale that eddie finally admits how affected he's been by the shooting—and even after all that, fandom still acts like eddie only had panic attacks because he was, uh (checks notes) too gay to function. i'm still so salty about it xD