Is there any other reason for this; my only pinkish discharge?

Ok so, it's not impossible for me to be what everyone's mind jumps to, but the internet is so full of theories that are barely legible. So i wondered if anyone here can help.

I know i'm probably worrying over nothing, but here are the details.

- My last period began on 16th October.

- My periods are very irregular, to the point there is no set pattern between them.

- I last had intercourse on the 11th and 12th October.

- Neither of us are sure of our fertile status, because we have never conceived children.

- He is 49 years of age, I am 23 (please keep your judgement as it's not valid in the answering of this question).

-Both he and i are clean, and up to date with doctors check ups.

- I had a minor pink vaginal discharge on 10th November, the 1st one i've ever had. It was brief, I got into the shower after i'd noticed it and by the time i left the shower it had gone. It was definitely coming from my uterus, i checked.

I don't want to jump to conclusions, and i don't want to waste money on a pregnancy test at this early stage when it may even be too soon to tell. I just wondered if there could be more reasons for this one occurrence than implantation bleeding, based on the information i have. Especially since i have never experienced it before.

Any help, is greatly appreciated.