So I went to the library after work and wrote a little bit of Inter Vivos - only about 200 words or so - and only focused on that, not on the other projects that are making me flip out. And then I felt better. And then I went to watch Star Trek, which was brilliant, so I'm all alright now.
Just goes to show you how quickly a mood can change though, right - from walking to the library feeling like I was mentally hyperventaliating to leaving the library feeling much calmer and happier.
Anyhow, I'm going to take it slowly over the next few days and try not to pressure myself too much.
I think I do definitely need that holiday now!