Chronic Infection Surgical Site/Mouth

Need advice. Had orthognathic surgery (lower jaw moved back 2mm) on Dec 7 surgery seemed like a success but after about 2 weeks my OS noticed that the wounds weren't healing. I was prescribed: Clindamycin (1 week 4 300mg daily), then Bactrim and them Z-Pack and nothing was responding. So on January 4th I had a second surgery.. he decided to take out the plates and screws and banded me shut for 3 weeks. Everything seemed fine until last week and now I have inflammatory tissue (localized infection) at both surgical wound sites. I am freaking out and now I am back on Clindamycin (1 week 4 300mg daily) and he took a culture of the infection. I am confused because I had a complete physical last Weds everything came out normal (CBC, Chem 7, PT, PTT, Ekg, Chest Xray etc) and had my yearly pap less than 2 months ago. Is my immune system low? If this is an infection why didn't it show up on my CBC? Why isn't my body responding well to the antibiotics? What can prohibit my body to completely heal the wounds? Anyone please help.