Piriformis syndrome

Hey y’all! It’s week 2 of intentional marathon training and I think I’ve already injured myself. I ran 13.1 miles last Saturday and felt great, until I later noticed a deep butt pain on my left side. I’m pretty fit (before recent training, I’ve done hot yoga 5+x a week with 1 - 2 long runs) but I really overestimated my hilly route and I’m guessing my running form really suffered in the end. The pain is mild and I can still run but any tips for recovery? I’m flexible and stretching doesn’t help much.

I’m scared I’m already out of the game before even starting. Marathon date is June 1st.