Wearing either my metal cage or my cb, sometimes my left buddy seems to get turned around or twisted in the sack and it is like someone squeezing/pinching my left nut. Anyone ever have this issue? I sometimes can readjust and it helps. Sometimes I have to take it off and start over.
I've had one slip through the ring gap before I found the right cage/ring. Sort of like mini ball busting I guess!
Put a hair tie or something around your two testicles to keep them where they belong until you get used to wearing a smaller base ring. Gonna take a wild guess here and say you are probably using a 50mm base ring or a 2 inch diameter... Just make sure if you deicide to "tie them off" it isn't too tight, you could also use something like a very flexible cock ring.
I actually have this same issue sometimes and it has ultimately kept me from going full time in a CB style device for years. Upon observation it appears that my left nut rests higher than my right one so maybe thats why it feels like my left one is getting pinched