(and no, I don't think social science is a real science)
You don't need to study this stuff professionally to see what's going on here.
1) Trust in institutions has been falling steadily for a long time. That's because modern institutions are not trustworthy. Vast conspiracies were posited, laughed off as tin-foil-hattery, and later exposed as true (Snowden being the canonical example). Large federal governments like the US Federal Govt and the EU became more and more opaque, with ever larger and more byzantine bureaucracies and regulatory frameworks that seemed to create a game of tails we win, heads you lose. Judges interpret the law to suit their political preferences, not what a plain reading or common sense would seem to imply. And so on.
2) Whilst trust in institutions has been falling steadily for a long time, trust in the mainstream media has collapsed dramatically in relatively recent times. This too is fully deserved: people don't trust the traditional news outlets (in the USA) because they lie a lot and are nakedly biased. The difficulty of finding any national newspapers that supported Trump and the practice of outlets that had never declared before in their history declaring for the 100% globalist/liberal-elite-style Clinton, summed this phenomenon up. The subsequent artificial mass hysteria over Russia and the (dubious at best) Russian "hacking" of the election reinforced this idea: the media is as locked in a form of groupthink as Washington itself is.
You can't repeatedly teach people that there are no reliable sources of information, and that conspiracy theories are sometimes real, and then act surprised when large numbers of people start seeking out alternative sources of information that more frequently support conspiracy theories.