I would be inclined to think it is a UTI, I have suffered from them chronically since I was about 14 and now get them without realising. When I was pg with my DS I had one and didn't notice until it spread to my kidneys which was awful. You don't even need an appointment to get it checked out. Go to your GP surgery, ask at reception for a bottle and leave a sample with them this morning.
Better that you checked over nothing rather than miss something that became serious. None of these pains tend to be mentioned in the pregnancy books! Glad it's nothing to worry about. Hopefully it'll just pass soon.
If it persists you could go and get another sample checked in a few days at the GP. I had what I thought were symptoms of a uti at 16 ish weeks but had a clear sample ( in fact 2) and the third time I went and got it checked, a week later, the infection showed up clearly. They said it had probably been 'brewing'! But I have also had non - uti related weird pains and feelings of pressure or urgency at various points. Annoying but seems to be normal