Sick after Travel.. Why?!?

Ok, if anyone has an explanation for why this keeps happening, I'd love to hear it: after every vacation, adventure, back in nature trip, multi day cycling... I get seriously sick!?!

Let's rewind the travels of the past few years.

After Barcelona I had a cold and for a couple of weeks I was fighting something that looked like a virus.

After Nice, I went through a similar thing, except I had to include antibiotics in the process.

I came back from Rome with a lot of blisters, but luckily I wasn't in pain, apart from being chronically tired.

I came back from Iceland in really bad physical shape due to a wrist injury on the hikes, and another cold followed that.

The second trip to Nice went a little better, if you don't count the fact that I had a slight cold in Nice.

Madeira was extra, but I already started antibiotic treatment there since it was obvious I had a sore throat.

Copenhagen was calm, but already in the Dolomites I suffered a serious eye injury from which I was recovering for several months.

The last two trips to Lisbon ended with colds upon return.

Now, after returning from the Azores, I got a sore throat and am on antibiotics again 😕

I know my throat is very sensitive, but all illnesses seem to come on after traveling and vacationing. What do you think about that? Any advises?