blood tests for heavy metals are inaccurate... especially in the case of a chronic poisoning condition. even challenge tests can be inaccurate.
the best method i am aware of to test is getting a hair mineral test and using andrew cutler's counting rules. ( you will have to look it up in his forum or buy his book) and even in this case, cutler himself admits the hair tests are not 100% accurate which is why he recommends also doing an empirical test... that is taking a small dose of a chelator and noticing any dramatic changes.
raw diets will not only stir up metals but all sorts of toxins. this is why coffee enemas were such a crucial part of the gerson program which involved a lot of raw juicing.
dr. gerson was keenly aware of the importance of clearing out the liver while undertaking very aggressive body cleansing.
there is the possibility too of deficiency, but you said you returned to a balanced diet and that did not resolve the situation. there is also the possibility of another source of toxicity that happened coincidentally to the time you switched diets.