I keep getting colds/sinus infections/bronchitis! Help!!

I’m so freaking miserable. I’m only 25 weeks pregnant and I’ve had to take antibiotics 3 times now. I just finished Augmentin a week ago and now I’m back to being congested in my chest and my ears feel so stuffed. I just want to cry! I’ve been constantly getting sick since 5 weeks pregnant! I don’t know what to do and I don’t want to keep pumping my baby full of antibiotics that aren’t working any way. Hot tea with lemon doesn’t work. Humidifiers don’t work. Any advice?