You don't necessarily have to seek out another professional to fix it as there is only really so much they can do. The main thing is that they will sell you a leave in conditioner or a conditioning treatment. For over processed hair, there isn't really a way to "process" it back. You just have to condition the holy heck out of it and with a bit of time and some TLC it will get better.
I like Paul Mitchell's "The Conditioner". Nexxus has (had?) some great conditioners, "Keraphix" and "Humectress" - but I don't know if it's the same as it used to be. (They changed their formula and opened themselves up to selling to the public. Boo.) Redkin also makes some good products.
The main things you want to look for in a conditioner is that it is compatible for your hair type, smells good to you and is a professional grade product. You can either go to any salon that sells product or go to some Sally Beauty Supply (or some other one that's open to the public.)
I have fine hair also and I recently over processed my own hair... long story but I put in some temporary hair color for a costume party and then had to strip it out. Paul Mitchell has been my savior. It brings my hair back to soft and bouncy instead of dry and frizzy. I tend to put in a generous amount - a little under a half tablespoon (my hair is shoulder length and not thick). One application trick is to lightly towel dry your hair after application so you pull out the excess - keeps your hair from getting weighed down and greasy feeling.
(I'm not a professional but I grew up in a family of hair dressers.