Poorly beardie

Hiya my sons beardie is 3yes old
he is really pale and has a black beard he never has this
he's really quite and seems really tired he's been to the toilet 3 days running normally once a week and today's one didn't smell good
He's not shedding any advice would be Good

I agree, if he's got a black beard that indicates he's in pain of some sort and needs to see an experienced reptile vet ASAP. The smelly poop may be an indication of parasites/worms or a bacterial infection like coccidia, so I'd get a fresh sample of poop in a Ziploc bag and take it with you to have a fecal done. Either way, if he has a black beard I usually just say that he needs to see a vet immediately because he's feeling at the very least a lot of discomfort, at worst he's in severe pain. Reptiles hide their illnesses and injuries very, very well, it's a survival instinct in the wild, as if they appear weak or sick they become easy targets for predators. So by the time they are black bearding and showing pain it's bad and needs addressed ASAP.

Need much more information and details on your beardie's setup and your husbandry otherwise we can't even hazard a guess.

Here's my Cheat Sheet :
viewtopic.php?f=6&t=234738&p=1806050#p1806050

If you work through it methodically , the chances are there are likely a lot of issues that need to be tweeked or changed and they will pop right out at you, if you can give very detailed answers we will then be in a position to offer help. Is impossible to help you if you don't provide thorough details .

A constant black beard is very bad sign when it's related to beardie health issues.
It will be very wise to involve a reptile vet as it appears your bearded dragon has serious health issues. Are you in a position to afford to take him to a good reptile vet should this prove necessary ?

A vet appointment with a good reptile vet is probably best made your highest priority ATM.

Before you go to my cheatsheet and go methodically through it.
Q1 / what is the substrate ( not that I think your's is impacted but it could the substrate harboring something nasty that's made him sick )
Q2 / UV source
>>a) age
>>b) brand
>>c) type and wattage and %UVB rating
>>d) reflector behind it
>>e) ontop a mesh/screen lid ?
>>f) how far from basking spot
Q3 / temperatures
Q4 / diet and feeding schedule

Any update of your beardie? Is he still black bearding? Were you able to get him to a vet?