I got this one from my sister who is a massage therapist and I believe it’s pretty cheap on Amazon. It’s about the size of an old school iPod and the cords make it look like one too. Haha good for being discrete. The sticky pads do loose the stick but I’ve had good luck washing them. I use mine for shoulder and neck related tension mostly but I’ve used it on the low back and my husband used it all over too.

https://www.amazon.com/dp/B01I17W3I0/?tag=bestviewsre-g-20

I hope you can find something good for you. Side note. I personally prefer ice to heat even though heat temporarily feels better ice helps me feel better faster, not sure if that’s a personal preference or what but just a thought. I buy the soft ice bags with the screw tops and do 2:1 water:rubbing alcohol to make gel ice packs that I can reuse.