Implantation bleeding?

I am 13 DPO today. This morning when I went to the restroom I noticed my underwear had a brown/ yellow stain on them. I wiped but nothing got on toilet paper. I have used the restroom several times after this and no AF has arrived. I have had several cramps on and off. AF supposed to arrive today or tomorrow, I have pretty normal cycles. I did notice I am salivating more than usual and I’m pretty tired/ sleepy. I’m scared to test bc I do not want to see a BFN. Did any of you experience these symptoms and got a BFP?