Dull back ache on lower left back. Test?

I had vaginal pressure feeling with no other symptoms. No bacteria in urine test but dr advised to complete antibiotics course for uti. Been 3 days now. I hav dull ache in  lower back. And i feel something tender while peeing Last year also i had similar feeling my gynaec gave me medicinie for PID after examination. This time i had to visit other gynaec due to lockdown. We are ttc for past 16months. Had medical abortion in june 2018 at 22 weeks. All related tests were done and no problem was found. Weak cervix was suspected. Plz advice if i should repeat PID medicine. My lmp was 25th april. I felt my ovulation was also late for very first time. I feel pain for that so i can judge. Plz help as doctors do not touch patients in our area physical examination is not possible it seems. I want to rule out any other infection. Urine routine was not having bacteria. Shall i go for any blood test?? No itching no discharge no foul smell only dull back ache and tenderness down there.