When I dragged and dropped the "iPhoto Library" into iPhoto,
That's importing an library into another library and is the wrong thing to do. What that does is import every image file, originals. modified, thumbnails, etc., into the new iPhoto liblrary as original photo. You lose the metadata, keepsakes, slideshows, books, etc., and keywords.
If you still have the iPHoto library on the jump drive do the following:
1 - move your current iPhoto Library from the Pictures folder to the Trash bin in the Dock.
2 - drag/copy the iPhotoi Library that's on the jump drive into the Pictures folder on your Mac.
3 - launch iPhoto and it will open the library in the Pictures folder and you'll have your original events, albums, keywords, etc..