Implantation bleeding?

My last period was November 20th and it lasted for about 2 weeks (periods are weird for me). App says I ovulated 4 days ago but only had sex once during that time and it was after app said I ovulated plus didn’t have ovulation symptoms. Period not due till 18th of this month. We did have sex a couple times week before last and I was still spotting from period but also had cramps and egg white cervical fluid during that time (my usual ovulation symptoms). I didn’t have any of that discharge this last week when I was supposedly ovulating according to the app. I know it is possible to ovulate early but I didn’t track so have no idea on when it would have happened if I did but I just went to bathroom and had a lot of stringy discharge mixed with light brown (tmi sorry). My period isn’t due for a little over a week from now. I never have spotting between periods. Could this possibly be implantation spotting? I will keep an eye on it but it’s just unusual to me so looking for some ideas on what could be going on. We have not had sex for a couple days so I know it’s not an irritated cervix or anything like that. Last day of unprotected sex was Saturday and if my app is correct I’d only be 4 dpo today but again no sex other than that one day AFTER it said I ovulated and I know it would be too early for implantation bleeding if I was really 4 dpo. I could have ovulated the day we had sex but that would only be 2 days ago and way too early for any implantation spotting. I have been having back pain, mild cramping, fatigue, and super hungry along with headaches but that’s not too out of the norm for me around ovulation and period time. It is a bit early for it to be pms I think tho. Any ideas on what could be going on?