I'm experiencing this right now RO, I've got 20 months and I've been sick so many times in those 20 months I've lost count! I hardly ever used to get sick! (apart from the death-warmed-over feeling I had every day, lol)
imho, I think for me it's a mixture of things: immune system changing/developing, strong bugs this year and still learning how to take care of myself. Now I eat well, exercise and sleep well regularly. But still I get every little bug that goes around! I will say, I don't seem to get them as bad as everyone else.
Again just my humble opinion, but for me, I never noticed how I felt before because I was always too hungover, or even just tired. Now it's my job to notice how I feel, so I can make sure my sobriety is secure.
Take good care of yourself, (I think) this too shall pass!