Have you considered peri-menopause? It's on the list of symptoms. Foggy thinking. I remember it well myself, she says at 57. My girlfriend and I had lunch. We tried to converse.

"Do you remember whatchamacallit?"
"Um, give me another clue."
"Oh, you know, that thingie, the...the...what's her face's cousin, what's her name had it. You remember..."
"I think I do..."

We giggled all the way home. We figured the people in the restaurant must have thought we were nuts. We understood perfectly what each other were saying, but we couldn't remember the words. For me, it passed. At the time, I was terrified that I was already going senile.