[dcmd_crash]

You'd have to create a function and put that function on a timer, for example:

pawn Code:

forward DrawNewHealth(playerid);
public DrawNewHealth(playerid)
{
    new Float:pHealth, string[128];
    GetPlayerHealth(playerid, pHealth);
    format(string, sizeof(string), "Health %f", pHealth);
    TextDrawSetString(TEXTDRAWNAME, string) // this is where you would update the actual textdraw
    return 1;
}

Then set that on a timer whenever you show the textdraw, maybe OnGameModeInit?