Smelly/ dirty vent/ pale

[fatimastic]

My pullet should have turned old and egg giving by now. She is 8 months old. Her other friends have grown up and started laying eggs yet she is still underweight and small compared to them.
Recently i noticed a big difference between their sizes.

She is stinky, a bit lethargic , smelly and dirty vent and really small. Her tongue also seems yellowish. What should i do?

 

[ChickenCanoe]

IMHO, I would recommend boosting her microbiome. Normally a digestive issue which is what the messy vent indicates, can be attributed to either a primary pathogen like worms, bacteria or virus. Among those pathogens are also bad gut bacteria. If you don't have access to an avian beneficial bacteria like Gro2Max or a pet shop/vet sourced beneficial bacterial powder, try giving some plain yogurt or kefir. That can populate the gut with beneficial bacteria to crowd out the harmful bacteria.
What are you feeding?

 

[fatimastic]

IMHO, I would recommend boosting her microbiome. Normally a digestive issue which is what the messy vent indicates, can be attributed to either a primary pathogen like worms, bacteria or virus. Among those pathogens are also bad gut bacteria. If you don't have access to an avian beneficial bacteria like Gro2Max or a pet shop/vet sourced beneficial bacterial powder, try giving some plain yogurt or kefir. That can populate the gut with beneficial bacteria to crowd out the harmful bacteria.
What are you feeding?

Thank you for replying !
Im feeding them a normal seed diet.
Ive been giving her yogurt but there hasnt been much of an improvement.
Can you please tell dosage for the probiotics i found to give the flock?

 

[ChickenCanoe]

I think that is a human probiotic which is fine. I usually look at it as a per pound dosage. For infants, it should be 1-2 mini bottles each day so for a chicken, I would say one bottle spread over 2 days. How were you going to administer it? You could put it in her water which is the easiest or you could orally dose it, being careful not to aspirate the bird (getting it in the trachea). It would be hard to overdose it since it really isn't a chemical.
Since the other chickens are fine, I would make sure she gets all of it.
Is the seed mix what everyone uses to feed their chickens? It looks to be a blend of grain, legumes and other seeds.
Do your birds free range or have access to the outdoors? That would be helpful for them to get some animal protein in the form of invertebrates. Getting her some animal protein wouldn't hurt. Any meat, fish or fowl that you eat, even scrambled eggs would help.
Good luck.