Headache, hearing loss, damaged DNA, tendonitis, diarrhea, impaired kidney function damaged proteins and lipids in cells — all occasional side effects of long-term use (4 days!!) of antibiotics. Because antibiotics harm bacteria and leave tissue untouched, they seem safe. But they trigger oxidative stress in the bacteria which causes the side effects.
If you need to use antibiotics long-term, which is considered 4 days or longer, ask your doctor to consider less popular tetracycline or add an antioxidant such NAC (N-acetylcysteine). (Source: Wyss Institute, Harvard University)