Yes it can be false negative since you are on antibiotics for long time already. And since you are suffering again even after taking full dose of antibiotics for considerably long period of time, there is no point in taking them at all. Stop for a week and repeat the test.
Next Steps
homeopathy will give you permanent and complete relief in this condition. feel free to contact for treatment
Health Tips
taking antibiotics for long duration can cause side effects. homeopathic treatment will help you without any undue side effects.