Politics Stack Exchange is a question and answer site for people interested in governments, policies, and political processes. It only takes a minute to sign up.
Sign up to join this community
How do I find out if Donald Trump is coming to a place near me?
I went to his web-site, https://www.DonaldJTrump.com/, "Make America Great Again! | Donald J Trump for President", but there does not appear to be any systemic information about neither past nor present campaign trail stops anywhere.
Most of what you're looking for is actually on the official website you linked to, although it's an easy link to miss. See the screenshot below for the location of the Events link.
The Events page seems to only list upcoming events, not previous ones, so it won't tell you where he's been. I also found blog.4president.us, which appears to be trying to track all the news about all the candidates, and it includes (under the linked-to tag) posts about all his previous stops. It is, however, not working temporarily right now, but screenshot of when it worked is below. 
Finally, there's trumpstump2016.com, originally provided by PointlessSpike. Some people have had problems accessing it (update: not anymore), but it's working fine for me. Your mileage may vary, but you can see what it's supposed to look like below.
