I have a 13w old kitten. He came to me last week as he was unwanted by previous owner. I got him vaccinated last wednesday and he is due his 2nd shot in just over 2w

The previous owner gave me some worming liquid (johnsons syrup) which I gave him on monday as they said he was due a dose every 2w but im pretty sure he HAS worms and im not so sure this syrup is doing any good

What can I do? Can I try a different syrup/tablet/paste or should I just wait it out until his jab and ask advice their. I really dont like the thought of the little guy having worms (for his health and my kids!)

Any advice? I dont want to go buy another and overdose him, I was thinking about drontal tablets