I'm not sure. I know my libido was affected during my chemo but it was pretty non existent for awhile prior to that just because I was so sick, and we didn't know exactly what was wrong yet. Have you discussed it with your oncologist? Every cancer is different as is each chemo regime, it may or may not be the chemo drugs themselves ( I read up on the side effects of each of the chemo drugs I was given). It could be the stress of being sick, or exhaustion from that or the treatment itself.
I'm not sure if it's appropriate for your situation but I know that when my hematologist put me on prednisone for a short time right after I was diagnosed I felt completely euphoric and so much better.
I'm not sure if it's appropriate for your situation but I know that when my hematologist put me on prednisone for a short time right after I was diagnosed I felt completely euphoric and so much better.