Vijay's mistake -might contain spoilers-

Well, what now was it exactly that sooo pi..ed his father off?

I mean, I've just watched this movie, and it left me wondering. I mean, if I got it right, Vijay's troubles came from his back-problem, right? The one he wasn't told about, and thus, couldn't do anything about.
So, he didn't know how serious his health problem was and just took those injections as he was told to and had no idea what it all could (and finally would) turn out to be. (Sorry, if I lack sense, English is not my mother's tongue...^^)
I just don't understand why he didn't just explain things to his father (after things blew up) so he (the father) would understand.

Just would like to get some clarification on this point. So that I can understand the movie / the plot better. I feel like I'm missing something there.
I mean, after all, his father is soooo 'angry' with him for something that, as I see it, is not actually his son's fault at all. Not really.
Unless I missed some important clue. Which is possible, since I watched it with subtitles...

Any thoughts?
Thanks in advance.^^

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