Why do I burst into tears over something so stupid and irrational?

Lately I've started bursting into tears everytime I see pictures of the countryside. Its really freaking me out. What the hell is wrong with me. I went to the cotswolds with my boyfriend a few weeks ago, it was lovely. I'm not a particularly bursting into tears kind of person but the feeling I get when I burst into years is like a really emotional surge. It's unexplainable and stupid.