In an interview with The Independent, he said that he almost thought he was going die.
Now seemingly relaxed and self-assured Trescothick was not so six months ago. Then, he was sobbing uncontrollably in a corner at Dixons at Heathrow Airport, emotionally incapable of boarding a plane for Dubai with his Somerset teammates.
His recently published autobiography -- ''Coming Back To Me'' -- provides glimpses of the harrowing time he had when he quit the tour of India and later exited prematurely from the Ashes series in Australia, which England lost five to nil.
According to The Independent, the book should help to clarify the nature of his illness, although it can't help that there is no fancy name for it, other than the rather unsatisfactory "anxiety".
Trescothick believes that writing the book has had a cathartic effect on him.
"Yeah. It had all been in my mind for such a long time, so to get it on to paper almost cleared my mind, in a way. Also, it felt so bad in my mind, but it doesn't look quite so bad written down. I can see the good things that happened as well," he says.
He has enjoyed an England career that yielded 14 Test hundreds and a splendid Test average of 43.79.
"When I came back from India the first time, I didn't have a clue what was going on, except there was something drastically wrong. I thought I was going to die. And having to deal with that was a nightmare. When it happened again I had much more understanding. I knew I'd feel fine when I got home."
Trescothick was handed the captaincy on England's 2006 tour to India, after Michael Vaughan failed a fitness test. Yet he was in no fit state to think straight, let alone to captain the side.
At home, his wife Hayley was suffering post-natal depression following the birth of their daughter, Ellie.
This intensified Trescothick's own anxiety at being separated from his family. On the coach journey to the ground in Baroda for the final warm-up match against the Board President''s XI, the pitiful sight of beggars brought his mental anguish to a head. He lasted until the third day of the match, and then broke down in the dressing room.
In the book, he recalls: "At that point I was a shell. You could have taken all my kit, all my money, taken my life away. I didn''t care."
He was sent home that evening.
Significantly, even as a child he used to suffer from acute homesickness, so an international cricketing career was hardly what a psychiatrist would have ordered.
The man himself rarely dwells on what might have been.
"Well, of course I'd love to be involved. Who wouldn't? But I know I made the right decision, and that I'm a better person for it, away from the bubble of being an international cricketer. Obviously, there are massive financial implications. I'll have to keep working for a long time yet, whereas if I was still playing for England then who knows what my earning potential would be. I won''t be able to hang up my boots and spend my week on the golf course, like some will, and missing out on central contracts is a big thing, but I know that the price I would have paid was far greater than any reward," he adds.