Hi Lalb
If you had a week break on the combined pill this means your oestrogen levels will have fallen and also your progestogen. This mimics what happens after ovulation and just before the natural period and gives rise to the pms symptoms. Progesterone withdrawal is a well-known phenomenon giving rise to headaches, tension, irritiability etc. Decrease in oestrogen can cause low mood etc. So not ovulation as such but the same effects. If you had ovulated while on the pill then it would not have worked as a contraceptive although you say you don't need contraception? Taking back to back as you say, will keep your hormone levels stable.
The hormonal fluctuations will affect each woman differently so maybe the reduction is oestrogen and/or progesterone during that pill-free week is causing your sniffles and sore throat?
I hope your symptoms resolve once your levels are more stable.
Hurdity x