10 years out and gaining

I am 10 years out of surgery and gaining...HELP!

I'm 10 years out and I already gained. I'm trying to figure out what to do next, too.

I lost 100 lbs..held it off with little effort. .4.5years ago had a partial hysterectomy and Bam! 10lbs and it won't budge!! 

I'm worried so many peeps put weight back on...I'm hungrier and notice I can consume more .. discipline is a huge factor now.

FYI...I'm not big..I'm  5 ft @ 118 BUT remember I was smaller for so long then start gaining. So size not so much my worry its how I'm feeling about gaining and want to know WHY?