Honest help would be appreciated

Liz

I am 4DPO, but only according to OPKs. This evening I had slight pink/brown discharge (not much) and I’m worried it’s my period coming? I had been on nuvaring for years which I know can postpone/stop ovulation. Is this possible implantation bleeding? Next cycle I will be temping to be sure. I know I’m just getting anxious but would love some support.