Covid isolation. Any other blood test.

I started symptoms of covid on Tuesday 13th April with cough , back pain and low grade fever . Gradually I developed short of breath on 8th day , so I went to ct scan on 22/04/2021 in this the impression was alovera densities are found in bilateral lower lobes, with CO RAD 5 and CTSS RT 3/20 LT 1/20. He also suggested blood test d dimer , crp , s ferretin, cbc. CRP 2.5 mg/lt, d dimer is 511.9ngms/ml, FERRITIN is 139.9 ng/mL. My doctor suggested to take methylperdisone 40mg for 3 days, 32mg for 2 days, 8mg for 3days and 4 mg for 3 days.I have taken two  doses correctly and again on 26/04/21 he asked me to check CRP and D DIMER. In this CRP was 0.6 mg/Lt and D DIMER was 750 ngms/ml. He suggested me to take budecort rotacaps 200 for cough . Now I completed my isolation and came out. Is it normal or again the crp will rises when should I undergo rt pcr for negative or any other blood test .