Hi Stephanie - I know that you have said you are trying to avoid another surgery. But chelation therapy is used to remove heavy metals from the body once the source material is removed. For example, it may be used on children with lead poisoning once the source of lead paint is gone.
Since you still have the metal-on-metal hip implant, the rising chromium & cobalt levels are going to be a constant problem are going to continue until is is removed. Here is a partial list of the damage these metals can cause: soft tissue destruction, osteolysis (bone damage), neurological issues (such as tremor), endocrine issues, heart damage (cobalt).

This is what the CDC has to say about chromium poisoning:
"No proven antidote is available for chromium poisoning.
Treatment in cases of acute high-level chromium exposure is usually supportive and symptomatic.
Treatment consists of removal of the patient from further chromium exposure, reliance on the body’s naturally rapid clearance of the metal and symptomatic management.
The physician can provide advice and patient education regarding smoking cessation, how to avoid or minimize exposure to other known pulmonary carcinogens, and general preventive health measures."
(https://www.atsdr.cdc.gov/csem/chromium/treating_and_managing_chromium_exposure.html)

Here is more information about the source (the MOM implant) needing to be removed. https://www.drugwatch.com/hip-replacement/metallosis/

I don't think you are going to find a proven chelation method that will eliminate your issues unless you also remove the implant.
What have the doctors told you? Have you consulted a toxicology specialist?
Sue