Thanks very much for your help guys.
Good news today - he pooped! Phew! We waited nearly 7 days but got there in the end!
He is also back to a normal bed time routine on the last couple of nights and he is much more active - glass dancing etc. He even walked out onto my boyfriend's hand yesterday and took a bit of apple from us (still not eating veg from the bowl tho and only eating about 5-10 crickets a day). But hopefully he has adjusted now. We were anxious to make him happy but with a bit of patience he seems to be doing well now fingers crossed.
Thanks again for the tips. Much appreciate the advice.