Here’s what to do, in general. If he’s not eating, you’ll eventually end up starving it to death. I know you don’t want that. That’s a horrible way to die.
From what you’ve said, this is not going to go away on its own. You definitely need to take him to a vet. He’s obviously in pain and you said he was having convulsions. They are serious symptoms. Please take him to a vet.
The average life span of domestic cats is 12-18 years. Your cat is not old.
@Mintoeb Good evening to you all. I know you are probably busy, so when you have time, if you could possibly give us an update on the poor brown cat, that would be really great.
Thank you in advance!!
Good evening. Thank you for also taking an interest in his well-being.
The owner is going to take him to the vet soon, all we can do is take care of him and wait for the owner, we told her everything that happened to him yesterday.
Good evening! Thank you for the reply. And Prayers for the little guy 
Hello friends, I have a piece of bad news. I know our community adores pets… Unfortunately, poor cat passed away. Please be tactful and feel free to post your words of comfort 
May he rest in peace 
Thank you Kaya for sharing this news with us. Your update is appreciated.
I pass on to @Mintoeb and Tea Mint and anyone else involved, my thoughts at this sad time.
Sorry Lets, but you’re wrong: Mintoeb said that the cat is 13 years old. That corresponds to a human age of about 67 years. So it is not correct to say that the cat is not old.
Edit: wasn’t old. Rest in peace, TYOTYA-MOTYA. 
@Mintoeb This is heartbreaking news. I believe that Ally was on her way to take him to the vet? I am so sorry to all here who are involved in the poor cats life. I know from many personal experiences how it feels. But he is better now. No more suffering. Prayers to all !
Thank you for your words of support❤️
We will take good care of the black cat. Let’s forget the sad topic. Have a nice day and good mood everyone
I actually got that info from Mari a couple days ago…
“I contacted the owner of Mochi Ally, now we are solving this issue, thank you for writing the timing”
Unfortunately, the veterinarian said that there was a dental infection, there should have been a repeat appointment, but they did not have time, the baby died after falling asleep. The cat had a dental infection, had surgery in August, but the bone was affected…(
Poor guy.
Thank you for telling us and keeping us informed about such a sad situation.