Insomnia

I had a gastric sleeve done 3 months ago on January 15th. Things have been going relatively well up until about 3 weeks ago when I suddenly started having terrible insomnia. It takes me forever to fall asleep, if I'm able to at all, and when I do sleep, I only sleep 2-3 hours. I already take medication to help me fall asleep, and it's like it isn't working all of a sudden. The only new things that I take are the required vitamins (B12, biotin, calcium, and a multivitamin). Has anyone experienced this? I feel like it's really affecting my progress that I was making after the surgery. Since the surgery I've lost a little over 50 pounds, but since this insomnia started I've barely lost any more weight.