I went to the clinic this morning and spoke to a nurse who took a list of all my symptoms and was concerned that my IUD may be expelling. She took a pregnancy test (negative!) and then tested for a UTI and then got a doctor to come and examine me for signs of expulsion.
The doctor was the person who had fitted me with the IUD initially. She said she couldn't see any signs of expulsion right now but if the pain continued I was to go back. She swabbed me for BV and chlamydia and I'm expecting results in a couple of days.
Thanks for the feedback on the initial post, it was reassuring until I got medical attention today!