I had a very similar experience. I went to my General Practitioner for what I thought was a simple urinary tract infection. After several urine tests the lab results showed protein in urine or MM from kappa light chains. I had no MM symptoms . I started treatment shortly after.
My multiple myeloma team has resources to learn more about MM. I would start there to get some information listed under resources.

I think there is no one answer to your question. Count your blessings. I felt healthy as well I work out and eat healthy but kept having pain in my chest. The pain has subsided I agree the medication and side effects can cause more issues

I've had cml for 3 years and have never felt bad from the disease, my problem has been the medication . I'm now on an experimental drug that has me feeling much better. .I would say other then not being tired, I don't feel sick!