Something weird with my left leg? Medical? Helppp

So my left upper inner thigh started feeling raw, like something had been rubbing against it constantly when it hasn’t. It hurts so bad on and off, and honestly I first thought it was me getting stretch marks on my leg. Initially it was warm to the touch, too, but now it’s not. No discoloration, or anything like that.

Now, it’s going around my whole upper thigh, and the whole upper thigh feels raw as hell, nothing is warm to the touch and no discoloration. I have a baby check up on Monday, so I’m gonna ask about this etc BUT has anyone experienced this before? What could it be? It’s freaking me out a little because I (of course) WebMD’d it like an idiot lol.

I have to mention, I had surgery on my left knee a little over a month ago, and am on it less (but not that much less) than I was before. Only 2k less steps a day since 2 days post surgery.