A number of years ago, my partner and I purchased a half dozen top quality freshwater spinning rods. After one year of hard fishing we noticed that all of the blanks had fatigued considerably. We did not notice it casting as much as fish turning and control capability.
Also, run & gun boat fishing can certainly throw you off kilter abit. If you are used to fishing on foot and you don't wait till the boat stops to cast it can certainly throw slack into your shore stroke. Adjustments can be made for the residual boat motion, but it is certainly a different stroke than a shore stroke. Wind direction and required casting direction is also more variable on a boat.
Try someone elses rod and see if you stroke comes back for starters.
Certified Stan Gibbs Cape Cod Canal Classic Flyrodder