Help! Yeast Infection won’t go away.

So after taking antibiotics for a throat infection in February, at the end of the month I got a yeast infection and I’ve had it ever since. I have been to my doctors & OBGYN numerous times, I have gotten tested for std’s, got my blood sugar levels tested (to check for diabetes) & a culture. Everything came out fine except for the culture which says I have the Candida yeast. Since February I have been on numerous treatments. I’ve tried Diflucan, Monistat, Ovules, Terconazole, washing with vinegar, eating more yogurt, garlic and less sugar. I even tried putting garlic inside my vagina. I even haven’t had sex with my boyfriend since then. I am miserable as this is taking over my life and its so irritating. It burns and itches like crazy. My Obgyn says she has never in her whole career experienced a case like this. Has anyone ever been through this scenario? If so what worked? Should I get a second opinion? Please help me. I am so miserable over this. I just want to go back to having a healthy vagina.