Transmission worked on freeway then stopped engaging out

I was on the freeway driving going about 40-50 mph when all of a sudden I noticed that the RPMs we're climbing up to 7-8 and that I had lost all "connection" with my transmission because it would no longer engage. I checked the fluid and it was unusually high. I had just changed the filter a month ago so I know that I did not fill it that much. I think the fluid in side the torque converter mixed with the new fluid because this fluid was really dirty. I dropped the pan and noticed that when I did the filter fell right out. I filtered all the fluid,put a new filter gasket ring thing in there and bolted pan back on but still no luck before I go get another transmission is there any thing else I can check or to to get my pump going again???