@sallylynn Welcome to Mayo Clinic Connect. We kidney patients find that most primary care doctors don't seem to understand the issue of falling eGFR and kidney issues. Even some nephrologists do not seem to take our cases seriously until later. But you are right to be concerned, and advocate for your best health care possible! If your primary care will not refer you, go up the chain of command. Go to the patient advocate for your clinic, and demand a referral.

Watching your protein intake, along with sodium, phosphorous, calcium, and potassium will steer you towards a healthier kidney diet. Likewise, proper hydration. Moderate exercise is wonderful.

As to the causes of kidney disorders, it could be a medication reaction, diabetes, uncontrolled high blood pressure, or genetic factors. Do you take NSAIDs like Naproxen or aspirin? This can cause kidney issues; chronic kidney disease people are relegated to acetominophen [Tylenol] only for pain relief.

Bear in mind that different analyzing machines can produce varying results, as can your hydration level on a test day. or fasting/non-fasting.

I recently went onto Lisinopril. Prior to that I was on a medication that caused a lot of lymphodema. I titrated onto Lisinopril, now that I am on dialysis. As @windyshores mentioned, it can cause kidney issues. That is no longer as much of a concern for me.
Ginger