How is little Maximus feeling?

When you shower, take him into the bathroom with you, the steam will help him. Also wipe his face with a warm wet flannel.
If you have any eucalyptus or olbas oil put some on a tissue near his bed.

Thank you for best answer!

You need to get the kitten to a vet, urgently - little kittens can rapidly go downhill & if you don’t get the right help as soon as possible, you could lose him

He can only breath from his mouse?

You might get $10 at the local Chinese restaurant

How old is the kitten?
If it's breathing through it's mouth then it's sick, they usually breathe through the nose..
Feed him soft food, no milk or cheese..
Watch the litter box, make sure that he is peeing.
And check his poop..
It shouldn't be loose or runny..

Do the steamy bathroom three or four times a day. Use tissue to clear his nose and eyes. If he's not better in a day or so or seems worse at any point, think seriously about getting him to a vet.

Use normal saline you can drip it in his nostrils regularly. You can buy saline nasal drops if you want easier application because it can be a real challenge.

I just googled it and it says, humidity (which has been mentioned), make sure it has warm bedding and use a cotton ball dipped in warm water to wipe it's nose and eyes. Also it recommends heating up their food as they don't have a sense of smell and the warm food will be more appetizing. They duration is usually around 10 days.

If you have a baby with trouble breathing, or a kitten or any animal, then use a humidifier. You want warm steamy air where the kitten is located. If you own a humidifier put the kitten inside a very small room and run the humidifier. If you don't own a humidifier, boil water and put it in a bowl. Place the bowl on a table, and cover yourself, the kitten, and the bowl with a large towel or blanket.

Hold the kitten near the bowl so the steam can help him with his breathing.

If you have any Vicks vapo rub, or horseradish root in the house, place a tiny bit of the vapo-rub on the end of a Qtip and rub it on his upper lip.

If you have fresh horseradish root, grate about 1 tsp and place it in the palm of your hand and make a fist. Open your index finger slightly so the fumes can escape, and then hold your fist in front of the kitten's nose.

Other than that, make sure the kitten gets plenty of water, and he should be fine if he is healthy.

When I was in Turkey the cats all appeared homeless and very hungry, so your kitten is lucky to have a home. I hope you can find a vet to examine him.

Keep him warm, wrap him up, let him sleep.

Since you can't or won't take him to a vet, that's your only option.

Find a way to get that poor thing to a VET...there is ALWAYS a way!

I'm not a vet but is your cat in too much stress that his throat is closing down? Check it's nose. If it's wet then it's not sick. If it's dry? it's sick

Have you tried steam or a humidifier? It's hard since he can't do the work himself.