I don't know what to do. My child is constantly sick - with fever, dia…

I don't know what to do. My child is constantly sick - with fever, diarrhea, phlegm, cough. And it's constant. We can't go anywhere, we dress according to the weather for guests, nobody comes over. We live in an apartment, there's always one temperature in the air. We need to ventilate!!! Why do babies get sick so often I can't understand. It's hard, I'm scared ?!!! I'm such a bad mother that I can't see my son! I keep blaming myself for this. My husband is not home (he works on shifts) and we, Savely (that's our son's name), every time