What is up with my vigina??

Okay so I was masterbating when i started my period and now when i pee right at the end of my 'stream' it hurts. Its not a burn thought, its more like pressure. But this also doesn't happen ever time i pee. After i do pee i feel like i have to go right after but over time it slowly fades until i really have to go.

I also now have a bright pinkish mild looking rash on my inner thighs.

I think this might be a UTI but I've never had one so if it is what should do?