Hi Flora,
You might want to print and take this to your GI or Doctor. I see you are currently taking Rifampicin - this is a slightly different version approach using a combination of other antibiotics where they found remarkable success for PG.
Just click on the link and perhaps print it if you can and are interested. No harm in seeing what your doctor thinks of this treatment version.
Treatment of Refractory Crohn's Disease and Pyoderma Gangrenosum with a Combination Regimen of Rifaximin, Gentamicin and Metronidazole:
www.ncbi.nlm.nih.gov/pmc/articles/PMC4342856/All the best and I hope you see improvement soon regardless of which path you follow.