How many miles?

Hrm... happened to me right before my clutch went out

Anyways, what I used to do when it would have a hard time either shifting into fifth or when it would grind really badly, I would depress the clutch all the way down, and let the RPMs settle to less than 2K... it would shift smoothly at that RPM. Then I would give it gas, rev match to what it should be for freeway speeds at that gear, and let out the clutch. Worked for me for about 3 weeks, then the clutch died.

It might be good to have it checked out.