Not sure how this would work on the neck area ? I bought one of these after having torn ACL surgery several years ago. https://www.amazon.com/gp/product/B07VXHXG7Y Tens unit that is capable of providing some very intense pulses. Multiple patterns and levels of intensity to choose from and can run 2 sets of pads on separate A and B channels. Self adhesive pads are not too expensive and can be reused quite few times. Rectangular and small square pads are available. I still use it for stiff back or pulled/sore muscles on occasion. One word of warning if the electrodes come unhooked from the pads. Turn unit off before plugging them back in otherwise its an intense shock plugging the wires back into the pads with the unit on. | 
Stiff/tight neck, any “devices” to help ?
