Don't make your doctor guess what's wrong with you if you think you may have welding rod toxicity. Tell them straight out that you're at risk, and give them all the other information that they need to make an accurate diagnosis. Even if it turns out to be something else, you will have eliminated one possibility.
While the industry claims welding rods are perfectly safe, the National Electrical Manufacturer's Association's Arc Welding Section has made it clear that they know manganese fumes are toxic. You and your legal team should be sure to take advantage of this information in your case.