Hello,
Doxycycl hc contains doxycycline which is a tetracycline group of antibiotic. It is often used for acne treatment and the condition starts improving after a few days of starting the treatment.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.