Sweating is good for chelating, but only if used together with a chelator like DMSA. Metals get stuck in soft tissue in a person's body, a chelator pulls them out of their hiding places and sweating (among other things) can help them get the rest of the way out of the body.
Testing for metals is a complicated question. You would definitely need to have a challenge test (take a chelator first before having the test done), but even then there are questions about the accuracy of the tests. It's worth considering a heavy metals test, but negative doesn't always mean negative if you get my meaning.
If I were you, I would try to find a physician in your area who knows something about chelating (and the potential problems with testing) to get a heavy metals test done.