Apple Watch Battery charge dropping like a stone

In the last few weeks my Apple Watch SE Series 1 has not been able to retain any sort of battery charge. It was 100% charged when I put it on and less than 3 hours later, my watch was dead. I don’t understand. It’s up to date with software updates, I even put the battery into low power to try and extend but I am now wearing a watch for the 6 hours of my shift that isn’t working. Any suggestions. I had pressed side button and crown earlier today to do a forced shut down. Planned to do it again tmrw. TIA