I was diagnosed with pelvic inflammatory disease but took all my meds. still experiencing pelvic pain and pressure! could it be more serious?

Could be : You need to schedule follow up. Pid is a big deal. Abscesses can form requiring further treatment. See you doctor asap.

Yes, it could be. : Pelvic inflammatory disease may be difficult to treat with a single round of antibiotics. If you have persistent symptoms you should contact your doc and be seen and evaluated carefully as this can effect your future fertility and overall reproductive health.