Can Omni Drop Cause Pain In Kidney?

I have kidney pain x 3 weeks..took ampicillion 500 MG x3 per day x 7 days and it came back worse? Started again on ampicillion Sat. Feeling better..is it related to Omni drops? This is my second round of drops...1st round in Sept I did great... 2nd round January..notice back ache 3 weeks into it...then got scared and quit? I m guessing I need to change to bacterium or macrobid? What are your thoughts?