Whats going on with our friendship?

Oh my friggin gosh. So this "kid" is like my little bro, at one point I told him that and he said I was his best friend. Well, i'll text him and it takes forever for him to reply!!! then when he does it's usually: oh, ok, ha, lol, yup, noo, :D. and all the other smileys. When he finally replies in a full sentence he sends me another message saying: oh gtg. So, obviously I think he's busy, so I'll stop texting him, also i get all caught up in soccer and softball and don't have time. Then when I check my phone I have like 30 texts all from him saying, "heyyyy.. are you mad at me?" "ooooh where are you?" "are you still alive?" "helloooo?" and so on.. At first we used to call eachother everyday to catch up, we would talk about relationships and family issues, now we barely talk at all! Am i losing my best friend?