Yep PTSD mucks around with lots of normal body functions. I had thick healthy hair to below my backside in April this year. By June it looked like a load of rats had eaten back to my scalp, bald patches & sores everywhere. So I got the lot shaved off when I got back to a cooler climate & bought some really trendy hats & beanies. Nobody knew except for one person which was accidental. It had happened to me before, it was caused by PTSD. Yes I grieved for my long hair, which let's be honest, is a private part of your personality that is open to all to see. ( And comment on sometimes quite insensitive comments too) But the distress of losing your hair for whatever reason is highly underated. So, take above responses into account. Maybe if you can handle it, be brave hit a good hairdresser with the idea of cutting it right back so you don't have to stress about it, even if you keep losing your hair for a while longer, it doesn't seem to be so distressing when you can take back some control & losing really short hair isn't as bad as losing longer hair. But, don't colour it, or if you really do, try Henna (natural colour from dried root of Henna plant, but most hairdressers won't do it, takes a while to do & they like chemical dyes) - don't wash it every day. You may still keep losing your hair for a while longer, but with effective treatment for your PTSD, it does grow back. Till I stop losing it, I keep it extremely short & the few who have seen it & been shocked by the change & have said stupid things, I don't tell them why I did it. That just opens up a private discussion I don't want to tell them about... is I have PTSD etc. I usually say something akin to, "That's odd you are the ONLY person who doesn't love my new cut!" Or, if necessary I tell them to tell someone who really CARES about their opinion, or if you must say, "Of course I had to, it has to match my Brazilian". But, usually I revert to my normal response to stupid people which is, "Don't f**** look at me then" with a few more comments like, " I have always thought your hair could do with being cut off at your throat level. But, you might be much more nice than I am.
One last thing, I am sorry you have had such a bad collision, have scars to learn to live with, have lost your hair....and now PTSD, the scars nobody can see.