Unfortunately, the bedikah on the onah beinonit (30th day) is critical, and may not be omitted. (Even if it was unintentionally omitted, one may not resume relations until this bedikah is performed.)
While usually one may attribute bleeding from insertion of the IUD to trauma, this is not true during an onah, or around the time a woman expects her period.
If you wish to share with us more details about what caused you difficulty in completing the taharah process last month, we may be able to assist you with future situations of this nature.
Please feel free to get back to us with any further questions.
B'Hatzlacha!