Hi,
It does not sound your little guy is choking. What is the color of his mouth? Is it the normal color. It sounds like he has an infection (Fungus, Virus, bacterial or parasitic) of the mouth.
This is normally the result of environmental stress (incorrect temperature, humidity, light or food).
Are you able to post a photo of his mouth.
You also might want to find a reptile qualified vet to take a look at him. Just be aware of giving antibiotic - they can damage Tort's kidneys and some vets are very quick on applying them.
You can get some anti fungal (Sulphar) bath for shell - it might help putting that into his bathing bowl. You can get it from your pet shop or local vet - they use it in Turtle water to stop shell rot. If he is not eating, do not forget to soak him in warm water often.
Good luck with your little guy. and keep us updated on how he is going.