Cassette won't rewind, please help!

I just recorded onto a blank cassette (brand new), everything was hunky dory the first few playbacks but now all of a sudden it refuses to rewind. It still plays and fast forwards fine, and I can manually rewind it with my fingernail.

It's not the cassette player's fault because any other cassette I throw at it rewinds fine. Its just this one specific tape that refuses to rewind in my player.

Side note: If I flip the tape to side B, then I can rewind but not fast forward!

What gives? Any advice would be much appreciated. Thanks!

edit: added that side note.