UTI? Or something else?

My periods haven't been all that regular since having a baby 15 months ago and since they started back up I've been experiencing dryness, itching, and general thrush-like symptoms for a few days before my period starts and a few days after it ends.

This month I had some light spotting in the usual two week window that I come on and just assumed that a recent sudden weight loss (due to a severe vomiting bug) had affected my flow as has happened in the past. A few days afterwards I got my period, badly. Extreme cramping worse than contractions and very heavy bleeding which slowly dwindled and came to a stop two days ago, 6 days after it has started. Since then I've been having the same thrush like symptoms but have also been getting a pain down below. It started with a pin prick type pain when I urinated and over the past two days has progressed to a more intense burning pain but it's not there every time I pee, probably 75% of the times I go.

I'm unsure if the spotting and this pain are related or if I just have a UTI. I had unprotected sex about a month ago but pregnancy tests show negative. I'm certain it's not an STI- my partner and both got tested years ago when we started dating and are both faithful (yes I'm sure!)

Will be going together docs on Monday but was just wondering if anyone had experienced anything similar or can give any advice/insight?

Thanks