Yeast infection x 3?

Hello everyone with in 2 and a half month I've had 3 yeast infections. Or at least that's what I think it is. I don't think it's an std because I'm faithful to my husband unless hes not to me. But anyways I'm currently on number 3 as we speak. I'm trying to figure out why I keep getting them. I went from not getting any with in the 28 years of my life and I finally had one and it keeps coming back. I take the 7 day monastat and it goes away and in 3 weeks BAM! Back again. I finally made a appointment with my obgyn today but it's not till October 3rd. I hate having these things it puts a stop on my life idk what to do.😫😫😫😫😫😫