Oncologists are notoriously bad at identifying chemobrain, and my own experience is that they're not helpful with the fatigue that goes with it. The standard answer is "exercise."
But what you've described is cognitive fatigue, and it will make you tired all over. For some of us, it lasts long than others. I think the stats are skewed, however, and more of us are felled by this than are counted. My neuropsychologist said that neurosurgeons take the position "You can walk, you can talk. Go out and live your life." She has now added oncologists to this list. Unfortunately for their pat theory, brain injury from chemo is effectively the same as traumatic brain injury, whether they like it or not.
There's some useful information in this thread I started after a long absence from this board because of chemobrain/fatigue.
http://www.her2support.org/vbulletin...ad.php?t=62041
Here's a link to the book my neuropsychologist gave me, along with a link to the PDF I stuck in my dropbox for easy download. (The download from the site is in Word, which is fine for those who have it, but not so much for those who don't.)
http://tbiguide.com/
https://www.dropbox.com/s/5g97u6wd99...Guide.pdf?dl=0
Also, see this blog. Idelle is a member here. You'll find information in the blog as well as a link to purchase her her book, and it's very helpful.
http://yourbrainafterchemo.blogspot.com/
Another helpful resource is Shelli Kessler's book:
http://www.amazon.com/Improving-Cogn.../dp/1490367721
Here's a PDF of the NCCN Guidelines for Survivorship which includes what oncologists are supposed to be doing but don't. Antidepressants are the new valium. Doctors seem to need a pill to hand out when they don't know what else to do, and antidepressants are the flavor of the decade. On the other hand, if you're not on tamoxifen, Wellbutrin just might work. If you are on tamoxifen, Effexor might be useful, but only at the higher doses. (Serotonin is not the problem; norepinephrine and, to a lesser extent, dopamine are what need to be addressed.)
https://www.dropbox.com/s/ecz1amnacd...itive.pdf?dl=0
You could try emphasizing to your oncologist that this is affecting your quality of life and your ability to support yourself, and maybe it will light a fire. It didn't work for me, but you never know.
Just remember to stop pushing yourself to perform at the same level as before. Your brain needs time to heal, and if you push too hard, you'll set yourself back even further.
Also remember that you're most definitely not alone.