I would like to help, but do not think I can. If you and your partner have not been tested for other common STDs (gonorrhea, chlamydia, etc), be sure that is done (but I suspect these have been done already). Trich doesn't cause PID or infertility, and cervicitis not due to chlamydia or gonorrhea has never been shown to cause them either. Nonchlamydial cervicitis is a mystery in many ways, but does not appear to be harmul.
If you aren't confident either of your doctors are on top of things, get yet another opinion. If you are in a major metropolitan area (and perhaps elsewhere), you might be able to find a gynecologist who specializes in infections; there are such people at many academic medical centers, for example.
Good luck-- HHH, MD