Spotting before period; recently taken antibiotics

Hi

I had a medical check about six weeks ago and was told I had a urine infection and candida. I had not suffered from burning while urinating, nor had I been itching, so it was a 'surprise'.

I was given antibiotics, but just before I started taking them/knew about the infection, I had sex using just the pill.

Since taking the antibiotics, I have used the withdrawal method.

Today, 4-5 days before my next period, I started spotting dark 'dead' blood. Could I be pregnant?

Thanks for reading and your replies.