He coughed up blood? Does he have some sort of medical condition that would cause this? Make it normal?

Yes having a panic attack because of it is not a good thing- panic attacks are the worst- but I could maybe understand it a bit more connected to the coughing up blood thing. Hes young, and scared, and therefore that symptom of coughing up blood- well, enough to push him over thr top.

I know when I used to have panic attacks- especially when I was psychotic (or just being unrealistic) it was always helpful to me to have someone just- be there without immediately trying to push me back into reality. Someone just to listen until it was over. It was awful enough to have a panic attack without at the same time having to feel like a freak for having one.

So just be there for him. If he starts getting nervous about his health- dont dismiss it. Validate his feelings of the fear- let him speak even if you feel the need to immediately ‘fix’ the problem- and then when hes calm again, go in and talk to him further about things.