I wonder is electrical stimulation would help with your cramps? I get neck and back spasms occasionally (luckily, rarely) and I use a TENS/EMS device to help release the muscle. Not exactly like your cramps, but similar (I'm assuming you're talking about leg cramps). I do not use the TENS settings on the device ("Transcutaneous Electrical Nerve Stimulation"), I use the EMS settings ("Electrical Muscle Stimulation"). TENS is more a pain control technology whereas EMS is for tight muscles.
Here's where I got my unit:
https://www.lgmedsupply.com/
Specifically, I got this model, the "LG TEC Elite" (they are always on sale, with extra discounts, and come to around $120 or so):
https://www.lgmedsupply.com/lgelteunandm.html
There are five bazillion different TENS/EMS units for sale everywhere. You would probably save money and just get an EMS unit without the TENS. ou can get replacement electrode pads for them on Amazon for really cheap (compared to the prices at a medical supply place). There are good and bad electrodes - related to how well they stick to you - so buy something with a lot of positive ratings if you do the Amazon thing.
The one I got is battery or plugin. It's maybe a bit on the large size - you could clip it on your belt but probably not keep it in your pocket unless you have larger cargo pockets.
I bought an EMS only unit once. In a shopping mall. At one of those temporary kiosks out in the middle of the mall walkway. And you know what, that little Chinese made unit works just fine for relaxing a spasming muscle. It certainly doesn't have the flexibility, variety of settings, and TENS function of the higher end one I bought later. And it is rechargeable internal battery only. It's much smaller and the battery goes for many hours of use between charges. Yes, it feels like a cheap Chinese trinket but it's lasted for over a decade now and is still going strong. I think it was $89 in the mall. Which I though was quite high priced for as cheap as it felt, but the wife bought it anyway. And really, bottom line, the silly thing works. If I could only have one unit, it would be the higher end TENS/EMS unit though.
The cheap Chinese unit has maybe eight different settings, of which I might use two. They are described as "bouncing pall", "rolling fist", etc. What the heck? Just find one that feels good (some can tickle of be painful). The better TENS/EMS unit can be configured every which way, but in the end I just pick something that feels good. You have your ramp time, your pulse width, your repeat rate, your decay time, your waveform, your amplitude, blah, blah, blah. You can hook up two pairs of electrodes and configure their placement as parallel or X-cross or whatever. A physical therapist might understand it, but I don't. I just stick the pads on where ever, randomly punch a few buttons until it feels good, and away I go. Always start off with the amplitude setting at low and move up from there. They probably all default to low on powerup. When you crank these things up - even the cheap Chinese one - you will fly out of your chair if you turn it up too high. Some settings hurt. Some setting tickle you to death. Don't put the electrodes on your chest across your heart. That would be worse than eating three handfuls of salt. It's not a
defibrillator ... I think it would be more of a fibrillator, not a good thing.
I have no idea if one of these things would be good for your cramps or not. But I got a neck cramp typing in this post. So I suppose I should go get mine and fire it up.