My ex says he's been "thinking about me a lot lately"?

We started as acquaintances that went to high school together (he's 2 years above me) and eventually started to hang out and become friends in November 2012. I knew I liked him right away but he was hard to read. By the end of December 2012 we stopped talking and I ended up moving across the country. In June of 2013 he got in contact with me and we started talking as friends just catching up. By August we liked each other. I decided to take a vacation back home (where he lives) for 2.5 weeks for Christmas. We were so excited and seeing him for the first time was incredible, a feeling I've never experienced. On my vacation we took a mini vacation to a little Christmas town and had so much fun and on the first night there in our hotel he asked me to be his gf. We were inseparable my whole trip and even met each other's families. We discussed how we were going to do this after I left and we wanted to still be together but have a date that I would move back and live with him. We settled for April and he was very nervous of the distance thing but I let him make the decision and he still wanted to give it a shot.

December 31st I left and within 2 days of me being gone he was distant and depressed like. Finally I called him and he said he couldn't do it. It hurt me so bad. And after that he basically fell off the planet not responding to (the few) texts I sent him.

Until last night he said he has been thinking about me a lot. I'm so confused. What should I do?