Interesting collection of symptoms and signs !
A few comments on CTS.
- The symptoms will be aggravated if the wrist is not in neutral i.e. the wrist is flexed or extended. The latter is often seen when people use computer keyboards and mice not to mention tools.
- Gripping compromises the nerve as it is the least able of the structures in the carpal tunnel to withstand pressure. (Consider what you did in the gym ?)
- Vibration also affects the nerves and could explain the response you mentioned.
- In the USA CTS is frequently diagnosed in office and assembly workers based on the symptoms and it fits under the umbrella term of Cumulative Trauma Disorders (CTD's) but in other countries different terms are used e.g Upper Limb Disorder ULD (UK) or Occupational Overuse Syndrome OOS (Aust). Unfortunately, these terms are all a bit meaningless.
- Night splints can be useful but only use at night.
- A bilateral problem could also be caused by dysfunction further a field e.g. neck degeneration. This is more likely if you have what is described as a poking chin posture.
- It is prudent not to rush into surgery until the real cause has been identified.
Some of the less common "rheumatic / arthritic" i.e. inflammatory conditions do have skin associations e.g. psoratic arthritis. Some of these conditions can come and go quickly but are often best managed with medication.
Low back pain. Have you read "Treat your own Back" by Robin McKenzie ? This Kiwi has produced an excellent laymans guide to self management and it is an inexpensive. It is published by Spinal Publications. The techniques advocated by McKenzie are used worldwide with great success.
Good luck on getting your problems sorted but in the meantime monitor what makes your symptoms better as well as worse.