Pre mom OPK?

Hi! This is our 2nd month TTC # 2. I used opk’s with her so I’m not a newbie.

I usually have a dark surge, that lasts at least 2-3 days and very strong O pains/discharge. I’ve never had to question a positive. I got this yesterday and I don’t feel anything. To me, it doesn’t -look- like my normal positive?! I re-scanned it twice and came back as high for both readings. This morning, back down to low!? Can this happen? A quick surge for a random month and I missed it? I am going to re-test again in a few hours to see. We had sex the 14,16 and will tonight and tomorrow incase it is!