There are other supplements other than obimin. First you should ask gynae to help identify via tests what you are allergic to so that you can take alternative supplements accordingly.
Perhaps you can ask doctor to prrscribe you with an alternative medication since u said you are allergic to obimin. In the meantime, have a nutrious and balanced diet for your meals.
Try to drink more milk, take calcium if you are not allergy to calcium. Can try taking fish oil too (for DHA).