My bestfriend of 2 years sends me the most confusing mixed signals, help? (2nd posting)?

Im a girl, he's a guy.. I'm 2 years older than him, Im 22, hes 20. It's funny, even though we're just friends people often confuse us as more. Needless to say I do have feelings for him, however these feelings are inconsistent. 1 minute I want us to be more, the next he's just my bestie. But there are so many things that he does that make me question everything. Like how he gets all irritated if I'm texting, but in a playful way. Then he'll start texting or get on his phone too, just to see how I'll react. For example, one of my friends txted me, and my bestfriend asked who it was.. And just to mess with him all I said was, "oh nobody, just some friend". Pretty much all my friends are guys, so I just left it at that. Then he started texting, and I asked who he was texting. His response was, "some girl".. Stupid right, lol?? Idk, then pardon my language, he's the biggest c**k block! It never fails. If we're around other guys, he'll stand a little closer, or call me by my nickname, or just be more playful than usual. Also, if a guy walks by, it's like he watches me to see if I'm gonna check him out or not, lol. But truth be told I do the same -_- But then there's other times when we're around one specific mutual friend of ours, and he's like, "OoOo look at her she's hot", in reference to some random chick ofcourse. We flirt too, nothing serious though, just little things. I go to the gym quite often too. However, any time I even mention the gym, his whole attitude changes. It's like he tenses up, or won't text me back! Thats what I think confuses me the most. it's just the gym, what's the problem? I don't know, I just need advise. I'm not sure if I should tell him how I feel, or if it would just complicate things, especially if he doesnt have any feelings for me too. What would you do? I dont want to mess up anything good we have. I mean he's my bestfriend, we hang out everyday. He's the only person in the world I can be my 100% complete self around. Please Help??