Missed pill, doubled up, side effects?

I am on the combo pill since probably July of 2017 when I stopped breastfeeding my son. I’ve had to change types once due to breakthrough bleeding off and on for probably 2 months straight, and this happened around February of 2018. I’ve been on Ethinyl Estradiol/Norgestimate since then with no issues. However, last week I missed my Thursday pill and didn’t realize it until Friday when I went to take that dose. When I saw this, I took both pills at once and resumed my normal schedule yesterday. I’m a Sunday starter, so these were near the end of my week of pills and this was week 2 of the active ones. Since then, I’ve had nausea, and today I’ve had diarrhea. Now I have questions.

1. Did I even take those correctly having missed a dose?

2. Could my GI issues be related to doubling up on Friday?

3. How effective will my pills be now? Or am I screwed until this pack is done and I have my period and start a new pack?

I’ve always been the person with the perfect track record taking my birth control up to now so I’ve not really paid much attention to the instructions on what to do if I miss one.

Thanks in advance!