I Just Been Diagnosed At The Sex Clinic As Having

I just been diagnosed at the sex clinic as having a NGU (and possibly chlamydia but waiting for test results, but an infection nonetheless). The doctor has prescribed me to take Doxycycline 100mg, 2 tablets for 7 days to clear it.

My girlfriend hasn't been tested yet but I assume she is likely to have caught it too. However, she have been taking Lymecycline (408mg, 1 per day) for a skin problem for the past few months. Could she have contracted the virus or would her Lymcycline intake prevent it or kill it off quickly if she did catch it? Also, to be on the safe side, would it be ok for her to take Doxycycline in addition to her Lymecycline just in case?

Thanks
Peter