1999 G20T shifting problems

[berdman]

Hopefully, someone can steer me in the right direction. I have a 1999 Infiniti G20T with a 5 speed. It has 2015k and runs right along. Lately, intermittently, after driving it for awhile, it is real hard to shift into all gears. I notice that when shifting into reverse, something doesn't stop or mesh, and I have to literally grind the gears to get into reverse. It continues until I reach home and park it. Then when the next time I drive it, it is fine, and shifts like butter, even into reverse without any issues. There is no rhyme or reason to when, where, how it happens, but it continues to intermittently happen. I would appreciate any guidance or feedback. Thank you.