int doNothingFlag;
This variable only takes on two values - 0 or 1. Making it a boolean, instead, would make your code much more readable.
int doNothingFlag = 0;
Of course, doing so will really screw things up when you have a local variable of the same name and different type. Local and global variables of the same name are rarely a good idea.
if ( (doNothingFlag == 0) && (now - lastCycleTime > mixer) )
{
doNothingFlag = 1;
would become:
if ( doNothingFlag && (now - lastCycleTime > mixer) )
{
doNothingFlag = false;
analogWrite(led, random(srumble,brumble));//Turn on LED for short or long burst
It is possible for brumble to have a value of 15, for example, while srumble has a value of 35, for example. This will cause random() to have issues, since there could be no valid value for it to return. How it deals with that, I do not know, but it is unlikely that analogWrite() will like that value as input.
}}
There are coding styles that call for the { on the same line as the statement that it goes with, and there are styles that call for it on a new line. There are no styles that allow multiple } on the same line.