Trump's biggest problems are that he declared war on the media (except Fox News), can't control what he says, and Twitter. Trump keeps fanning the flames and the media runs with it. He creates the hunt with his mouth and tweets and calls the media Witches for looking into them. If he would keep his mouth shut, work to get legislation passed, and keep his Twitter thoughts like a normal President, the media would not have Witch Hunts.
The reason for investigation between Trump and Russia is that Russia meddled in our election, this is a fact (maybe not in Fox News world, but the rest of the world knows it happened). Even Trump has now criticized how Obama handled it, so Trump must now realize they were involved.
Trump praised Putin during the election, appointed individuals that did not disclose ties/meetings with Russian officials, praised WikiLeaks for disclosing leaked/stolen documents, and asked Russia to find Clinton's emails. No one knows his or his family's business connections with Russia. He fires the FBI director because of how he was handling the Russia investigation. There are a lot of unknowns between Trump's campaign and business and Russia.
There maybe something there with Trump's campaign and Russia and there may not be, but it must be investigated. I personally don't think they colluded, but Trump needs the investigation to get completed quickly and should do everything in his power to expedite it.