okay, heres the story

im going down a street and all of a sudden the car starts bucking back and forth. then the car stops. try to start it, but it doesnt crank....i open the hood and theres smoke coming from the battery! i think it might have gotten tilted dwe to no battery box. so, now i disconnect the terminal and i try to start it. it turns over but wont catch. this happened earlier the same day and i let it sit and it started up. then this whole dillema happened. whaats going on? why is it bucking?why does the battery overheat, is it my altinator?

PLEASE HELP ME!