2 year old DS holding in poo

[ViviDeBOOvoir]

Does anyone have any experience of 'poo withholding'?
DS1 holds his poo in, sometimes for days and it's really affecting his/our quality of life because he can't relax until he's done it (and he smells until he's done it all).
He's pretty regular and needs a poo each morning but, for example this morning he's been complaining of tummy ache since he woke up and has been stopping himself from going. This means we can't go anywhere until he's done it as it stressed him out.
Only thing Doctor recommended is laxatives so he has no choice but I'm not very happy about that as he has a good diet and his poo is soft already and I don't feel happy about interfering with his urge to go (if that makes sense?!) he's 2.5.
Thanks.

Bump.

Might change my name to ViviDePoovoir.

Something warm like warm tea? Orange juice?
DD does this a bit too - usually though she holds it until there is a nappy on (ie nighttime); could you try that? Good luck. It's awful seeing them suffer, and there is so little you can really do! Although my DD finally mostly sorted this out just after I went on at her, chattily, about how no one grows up and goes to college without sorting this out, and that she was going to figure it out, and she needn't really worry about it. Somehow, just after that, she pooed on the potty! Not sure if there was any causal link there.
Another thing that helped her was watching videos on the potty, simply to encourage her to sit there, and also I guess to forget what she was doing.

Thanks for replying! After about a litre of orange juice he decided to go - during dinner of course!
Hers hoping there's not a repeat performance tomorrow!

Could he be ashamed of it? When DS (25 months) does one I make a point of saying absently what a lovely poo(!) before cleaning the potty so not too much fuss but keeps it positive. I once had pointed out to me children pick up on their parents' facial expressions changing nappies for example so I always made sure smiling even if smelly and any cheery conversation might help.
Just another idea but may not help!

Glycerin suppositories will force him to go, they were the key in my DS's two year battle with poo witholding (from 6 months to potty trained).