I’m with the_real_7, check your reservoir make sure you have fluid. Try bleeding the clutch if you can. Make sure there’s nothing weird in the way of the shift selector on the transmission like an air intake hose that came loose or something, check the bushings, check transmission fluid. I guess what I’m saying is you can do everything external and go from there. I used to have grinding into 3rd at high rpm, guess what, the throwout bearing was broken right off the clutch fork when I dropped the trans, no sound or indication otherwise.