Red/Green snake

Hi everyone! I’m new to having an Apple Watch I bought my Apple Watch February 20th and it is now April 20th. Recently my Apple Watch series 3 has not been charging and it’s starting to worry me, it stopped working 4 days ago and still will not charge. I checked to see if it was my charger and borrowed my sister charger but that was not the problem. It has a red snake most of the time and occasionally there is a green snake (which I assume it’s charging) sometimes the watch will show the Apple logo then turn off and it’s made it to 14% but then shuts right down again and then other times It won’t even turn on and it won’t let me reset it:( please help me because I’m starting to get worried about my investment in an apply watch