Have you considered some kind of mold growing wherever you live?

I had black mold in my apartment, and it would cause cold-like symptoms as well as depression and fatigue.

Depression and anxiety can also weaken your immune system.

What you need to do is go to a respiratory doctor (or a general practitioner) when you actually have "the cold", and have them test for a bacterial infection, flu, strep, etc. Certainly something will come up on the test. Maybe even a chest x-ray. If the doctors are shitty and unwilling to help, then it's not like one of the doctors here is going to be able to help you over the internet.

Usually when I get a cold more than once in a short period of time, it's because I'm getting sick with different strains of the cold. So like, if you travel from one side of your province to the other, then travel to a different province, you could theoretically get a cold 3 different times. But you shouldn't be getting the same cold, repeatedly, from the same community.

The other things to consider would be allergies, or some separate respiratory issue. Try a 24 hour non-drowsy allergy medicine like Claritan, and see if your "cold symptoms" go away.