i cannot scream for long, my throat clears itself?

i sing in a band but i also do abit(alot) of sreaming. i can scream well. i have been screaming for about a 2/3 of a year now but my throat keep like clearing itself and i cant keep it going for like say , the duration of a song. does anyone know about any methods ? or tips ? anything would be Appreciated =] thank you all ^^ (no hate mail please -.- my music is my music if you dont like it i dont care)
 
Top