Insert and alter a random number in pthread_create

I have this function to generate a random number.

int rand_lim(int limit) {
// return a random number between 0 and limit inclusive.
    int divisor = RAND_MAX/(limit+1);
    int retval;
    srand(time(NULL));
    do {
          retval = rand() / divisor;
    } while (retval > limit);

    return retval;
}

i call it like this:

srand(time(NULL));
int decrease = -rand_lim(10);

in order to get a random negative number up to 10.

Then when i call a pthread_create:

pthread_create(&thread,attr, change_number_thread, (void *)&decrease);

I want the number to be different every time.

The change_number_thread function is the below:

void * change_number_thread(void *n) // increments the x by i forever and prints it with delay (using delay function)
{ 
    int *i = (int*)n;
    while (1) // This way it loops forever
        { printf("Thread adjustment = %2i; x = %i\n", *i, x);
        x += *i;
        delay(rand()%MAXDELAY);
        }
        return n;

I can get a random number but because the pthread_create is in a loop i wish to have a different time every time.

Any thoughts?