I was told i have a pelvic abscess, but they don't know from where or why? they said wait 1 mos for any changes and come back. isn't it too long time?

Suspicious: If you have a pelvic abscess, you should at least have been given antibiotics. Small abscesses can resolve with just antibiotics. Larger abscesses have to be drained either by surgery or by image guidance (ct or ultrasound). Waiting a month with antibiotics could be appropriate if the abscess is small. If you are not on antibiotics you should ask your dr about them.

To long to wait : If, currently abcess present needs to be addressed. Can be related to the ovaries or colon , etc. If abscess resolved then waiting a month is ok.