Was your hair all virgin prior to using the med aubrun red permanent color?   What brand was the color? 

The roots are likely lighter than the rest of your hair because the color processes much more quickly due to the heat of your scalp.  Not sure why the rest of the hair didn't "change". 

You can put more color over right away.  However, I'd recommend using colorfix to remove the auburn prior to adding another color. 

What color exactly are you wanting your hair to look like?

Once the hair is damaged, nothing can be done to fix it.  However, there are products that can make it appear and feel better. 

I'd forgo the colorfix and focus on fixing just the roots at this point since it sounds like you have done so much to your hair in the past few months.  It's really best to decide on a color and pretty much stick with it.  The best way to change a color you currently have is to do some lowlights with a demi permanent, which usually washes out in a few months.  Try getting some John Frieda Firzz-Ease Hair Serum Extra Strenth (little purple bottle) apply some to the ends to help with dryness.  What kind of hair do you have, fine, curly, thin, thick, etc.?  There's a book you can purchase or check out at the library called, "Don't Go Shopping For Hair Care Products Without Me", by Paula Begoun...very worth the read!

It sounds like the ash brown you put on your hair must be darker than this auburn red you purchased and recently put on your hair.  Remember color cannot lighten color. 

I think your best bet thus far is to focus on fixing the roots.  You can probably get a medium ash brown and (strand test of course) touch up only the roots.   This should fix the reddish orange and leave you with a more reddish.  Don't pull this color to the ends, just do the roots and then rinse the hair out.

Now for changing your color, I'd really stick to doing something like a few lowlights or highlights.  You'll have to make sure you choose a color that is darker than what you have now in order for it to make a change.  (lowlights)  Hightlights require bleaching to a stage and then toning, much more involved.  However, I must caution you that if you have previously bleached parts of hair to white, that area will break if you rebleach over it. 

Maybe run out for another box of emergency brown cover dye and only put it on the roots, to make it match the rest at least a bit better.  Don't do the whole head, or it might make the problem more noticeable (take it from someone who's had variegated hair before from whole-heading when she didn't need to -_-;; ).