Actually you shouldn’t feel the kicks where you have placenta as it acts as a cushion. The same logic is why mother’s with anterior placenta don’t feel kicks till they are really strong. Your pain could be unrelated to the position of placenta. There are so many things going on inside us. The baby puts pressure on so many nerves and veins. There are things called lightning crotch etc etc. Could be any of those reasons. This is all from my own experience and whatever I have read online. The best advice can be given by your gynae. Check with her if the pain becomes unbearable.
Doctor informed me Low placenta at week 20 also. But now I’m week 25 and placenta have moved up. Also have the same sore feeling, doc said it’s because baby is breech and kicking me down there 🤣