Quit 2 months ago and have had 4 colds in that time

Has anyone had a similar experience? Is it related or coincidence?

I of course had other issues like headache in first week, and then extreme tiredness, napping most days which I never did before.

But I also picked up a cold and felt run down for maybe a week, and this has happened around 4 times including right now lying in bed and napping.

Could it be similar to getting sick on first day of a holiday where your body is finally able to relax and don’t gets sick