What is this? Please help?

Basically, me and my boyfriend were trying to have sex and it was really painful and turned out I had thrush.

I got given a tablet and cream and used them for the whole prescription period but we had sex yesterday and it was really really sore and painful and afterwards when I went to the toilet, it felt like I was peeing out fire and nails and I couldn't walk properly or sit down without it hurting.

I have a doctors appointment on Monday but I'm really worried.

What could it be?