I'd greatly appreciate any insight on how to fix and / or avoid this problem.

I've developed a roll of Tri-X as I have countless times in the past. I'm always extremely careful with my developing technique, and I've never had any problems in the past. However, on this roll, I have horizontal bands running the width of this negative, and to a lesser extent, a few other images on the roll. This is the last frame, and it's by far the worst. I've scanned it off the contact sheet. Any clues on what caused it? And better yet, any suggestions on how I might be able to fix it? I very much like this image.

Thanks in advance for any help.

- Cheryl