I have been taking tetracysal and differin (adapalene) to clear acne on my face. it was working ok for a week and then it became much worse on face and chest?

Be patient: I am assuming you are taking oral tetracycline and topical differin (adapalene) gel. In general I tell patients to wait at least 4-6 weeks before deciding a particular treatment works. Sometimes things will get worse before they get better.

Possibly normal: On occasion there is a flare up of acne lesions when starting therapy. It is important to make sure this isn't an allergic reaction is it you typical acne or a rash? Do you have antibiotic allergies? If this continues, begins to itch then speak to the doctor who prescribed the meds