Cat behaviour problem?

Greetings. I've been feeding a cat from the street that just showed up in my neighboorhood. Later I found out that his former owners were moving away from the neighboorhood, and they left him behind. And because of this, I felt very sorry for that particular cat because he's very friendly and cuddling, so I adopted him 6 months ago. I'am facing the following problems. He emewos excessively, especially the last few days now. I've tried to make him stop countless times, but it was futile. He's not sick or anything. I've taken him to the vet already. Besides all this, he has urinated 3-4 times in total in my house. What could be wrong? Is it that there's something that bothers him? Can cats get used indoors once they have lived outdoors before? I really don't know what to do. Please help. Thanks in advance.