Cat vomiting frequently?

He's a persian mix, and he's 2 years old.
He has vomited 5 times this week, 3 times on tuesday and twice today.
The vomit is yellowish and It mostly always has hair in it or a hairball.
I though maybe a hairball is stuck so I gave him a teene bit of petroleum jelly, and oil. But it doesnt seem to have worked.
He's otherwise normal, his poop is fine, he eats normal, he plays and is active and all.
Any idea of what it can be? I'm really confused since he looks fine

It does sound like he might have a hairball stuck in there.  Can you get your hands on some hairball remedy?  Maybe go to a pet supply store and buy some made specifically for that purpose.    I use Vet's Best Hariball and Digestive Relief.  If they have a hairball in there, it usually comes out within the same day I give it, and it's natural ingredients. 

I will to try to get some, though i dont know if I will find any, pet supplies are quite limited here.
Is there any other remedy that could work in case i dont find it?

Maybe something in this thread will help, but do check in your local stores,just to see what they have:

http://www.thecatsite.com/t/299988/what-do-you-do-for-hairballs

Also, you can even give him butter, but try to use unsalted.  Give him a little dab, or coconut oil. 

http://www.thecatsite.com/t/227971/vomiting-hairball-butter-or-vaseline

Thank you very much