Teenage sons weightless and smelly stools..

[Dickorydockwhatthe]

Ds is 15 and when changing I noticed he looks very thin and gaunt in the face. He has a big appetite but normally for the things!! He's been going out alot lately so has been eating fast foods. I don't think his diet is particularly great although I try to ensure we cook healthy meals when he eats at home. I've also no he's been going toilet quite a bit and his stools really stick almost like sick. He also has alot of wind(egg smell) and leakage tmi sorry. I'm just worried he's not right. He just looks pale and gaunt. Also noticed bruising or scaring along rib bones on his back not sure if it's related. He has a gf at moment and he mentioned she self harms he also has anxiety so my mind is probably overthinking

Well a visit to the GP would be a good start. It sounds like you are worried about multiple things so the GP might be able to untangle what is physical and what might be connected to the gf.

Probably at least worth a blood test to rule out coeliac.

You say leakage? Has it just been a little and how often?

Have a look at coeliacs disease and symptoms- they all fit, probably worth a blood test

Definitely worth a GP visit, especially with the weight loss.
It sounds like some sort of malabsorption- the stools get pale, can be runny, hard to flush and very smelly.

Any blood or mucous?