Confused: why did he act so teasing, caring, and what now ?

I met this guy at work and he is very nice:he walks me to my bus stop, once he's even brought me something to eat as I didn't have time to have breakfast. A few weeks ago, as he knew I had caught a cold he went buying me medicine.
Could he like me?
We are both 23. He teases me all the time when we're together verbally and physically sometimes (like blocking my way), the other day he burst into my office, I asked what he wanted and he said he just wanted to "tease" me. He's acted touchy once or twice, like a few weeks ago he put his hand on my lower back to guide me as we were entering a room.Once when i only replied shortly to his texts he panicked and said he got worried.
BUT he hasn't really asked me out or tried anything concrete. And lately he has started being less and less "present", he doesn't talk to me on fb anymore, and when I try he doesn't reply much.
What to think, why did his behaviour change? Should I make a move,and how ?

Either go after him of move on.

If you go after him, don't be afraid to get hurt. Getting hurt comes with the risk of finding love.

If you get hurt, move on. Think of him as a friend that you had a crush on in the past.

Wow, I really thinks he likes you! And maybe you weren't sending out the right signals, so now he's backing off. That's my theory anyway. But if you like the guy, time for you to go on the offensive by letting him know!

My guess would be the same as Susan's. I think he really likes/ed you but wasn't getting the right signals in return.