I don't have any medical knowledge or experience to answer your questions but I'm wondering if members in the following discussion might be able to share some tips or suggestions with you.

-- Muscle spasms years after hip replacement surgery: https://connect.mayoclinic.org/discussion/muscle-spasms-2-years-after-hip-replacement-surgery/

@jonpaulcobaltpo posted about metal allergy which you mentioned in your post possibly causing the spasms. I tagged the member but not sure they are still following the discussion. Here's the link to the post in the discussion above - https://connect.mayoclinic.org/comment/225491/.

I did find an article mentioning the connection that may provide more information. "2020 — More recently, systemic cobalt toxicity has been associated with metal-on-metal (MoM) total hip arthroplasty or shaving of cobalt-chromium ..." --- Cobalt-Induced Toxicity and Spasticity Secondary to Hip Arthroplasty: Case Report and Review of the Literature: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7842236/

Have you discussed the cramps with your doctor?