Cold turned sinus infection -- I'm 6 weeks pregnant?

I came down with a cold on Dec. 19, which got better around Christmas, but developed into a sinus infection on the 26th. I went to the doctor on the 29th and he gave me Ceftin, 250 MG twice a day for 10 days. I've been taking the antibiotics now for 6 days and I still feel exactly the same as I did when I first went to the doc. I only noticed improvement in my sinus drainage ... went from green/brown to clear, but I am still congested and really tired. I am worried since I am pregnant that my body may have lower immunity and I am struggling to fight off this infection. Normally once I take antibotics I am back to normal in a day or two. I plan to call my doctor again tomorrow but any advice on how to get through the rest of the weekend? I feel so miserable, it's hard to be happy about this pregnancy