thanks for writing in.
Missing a pill, and even otherwise, on birth control pills, it is not rare to have irregular/abnormal bleeding or spotting.
Do not cancel your appointment, as even with mild spotting, IUD can be inserted, but do not do it pre menstrually, as IUD is best inserted after a period is over.
Regarding your mood swings, frequent colds, tiredness
etc., please take vitamin C
and vitamin D supplements.
Also get your thyroid
Do away with any stress/ anxiety /emotional upheaval.
You can try yoga / relaxation breathing/ meditation
Also, eat healthy, eat right and exercise in moderation