Hi ? Ankle Sprain,

An interesting collection of history.

Starting at the beginning. When you lunge strongly you may cause injury to any of the components of the legs from the lower back to the hips, to the ankles and feet.

Two clues - an X Ray shows a chip off the Talus and the location of your symptoms vary from the Lateral Malleolus area and the Talus. I wonder if you have any other symptoms in the same leg and lower back, Hamstrings, Calf and other parts of the Foot.
If not then your problems are likely to be caused by the bone chip and possibly resultant inflammation of the Tendons and Ligaments in the area. The grinding, cracking, popping, locking and catching would be from problems in or about the tendons.

A CT Scan would be able to detect all Bone related problems and possibly Tendon problems. If the cause is the Bone Chip then a trip to an Orthopedic Surgeon is first on the list and then follow his advice, possibly excision of the chip. The related soft tissue symptoms won't subside completely until the cause has been fixed. Unfortunately minimal weight bearing is vital for a fix.
Good luck,
Tony Woodall. Physiotherapist - Retired.