How to see flights history close to my flight path?

HI Everyone!

Yesterday (Dec. 11th) I was on LX 38 from ZRH to SFO. At around 2:30pm Pacific time we where flying over Idaho, close to Boise when an American Airlines plane approach us from the right hand side and fly directly over our flight. It seemed to be very close as I could clearly see all the details of the AA plane. I know LX 38 was at 36,000 feet at the time and I would like to know how close we came to the AA flight. Does anyone know if there is a way that allows me to see what flights have been around that area at this time so see at what altitude the AA flight was flying at that time?
I was looking at FlightAware but I can’t seem to go back in time to see all flights in a given area at that time… Any pointers would be very much appreciated.

Thanks!