Implantation Blood or Period?

Patient: Hi. I am trying to puzzle if my discharge is implantation bleeding or period.My last period was on Nov. 25 and I’m expecting it on the Christmas Day, 25th. But– I have this discharge which is colored brown, associated with clear, thin fluid when I wiped using a tissue after I peed. I had an unprotected sex last Dec. 7 but we did the withdrawal. I know it is still mot safe but I am worried now.If I count it from my last period going now that it’s 24, it’s my 29th day cycle. Which means it is covered to my cycle days. I am so confused if this is period or implantation bleeding. Please help me. And the discharge is not just a spot or anything less. It’s like blood discharge.

Symptoms: Lower back ache and a little ache when touching my breasts. I do not drink much water and my sister said that my lower back ache could be my kidneys in pain. Is this true?