Hi Andy,
Sorry to reopen the chain again. The problem now I am facing is that as per your recommendation I started tracking users too along with keywords. Since this API or the follow tag requires user_id as a param I first did users/lookup and got the ID of all the users I wanted to scan (appx 500)
Now I am passing that user_id in the follow tag but I am getting tweets of some other screen_name. So I guess the problem is that my ID does not match with the actual screen_name although I have got that from the users/lookup API.
I would like to know how I can verify if the ID against my screen_name is correct or not. I see some of the IDs are correct since I am getting tweets of those screen_name so I am confused what exactly I have done wrong since I have followed the exact method and it works for some cases and does not for other.