Three days is not enough for a drop in my opinion. And even if it were to drop you sub-300, you’d most likely need a 2nd or 3rd, and possibly an MRI to rule out secondary, test to back the 1st number up if your doctor is following some sort of protocol… especially after two 300+ tests. What then? I don’t think you have this planned out.
I took mid-high doses of hdrol (75-100mg ED) for about a week (said to “suppress” after like 100mg) followed by 2 days off and then the blood test.
I dropped to mid 60s, but, I was naturally a 90-100.
Edit: Donate blood to drop your RBC and @norse_str3ngth is correct about CK. Mine always comes back high… I’m sure everyone else’s here is the same as well.