Does sound like carpal tunnel. However from the sounds of it the flexor muscles and ligaments seem to be involved.
you havnt said much about any tingling/ numbness - do you experience any
More Lilkerly is carpal joint aggravation possibility even a carpal bone fracture if there was a fall onto wrist at any point I would have this checked ASAP.
CPPD can a also effect this joint on a single side but if you bowel a lot it is more likely to be mechanical cause.
The scaphoid can offer significant complications if not identified quickly.
I would recommend a compression bandage (tubigrip) for the forearm in the mean time.
The wrist needs to be investigated quickly to be sure.
I would recommend ultrasound therapy and carpal manipulation to stop grinding (assuming fractures are ruled out)
Hope this helps