Why wont my LG Stylo 4 start charging?

For the last week my phone would make the movie I was watching small and bring up an Android fix it-fix it. I would dismiss it thinking it was nothing. Well, for the last two days I’ll have the phone plugged in to charge and on occasion log on to play a game. Well, each time the charge would go down. When I charged it it would only charge to 45%. Then to 25%. the to 7% yesterday. This morning 3-4%. This after noon it won’t charge at all. I finely figured out yesterday that the Android fix it deals that were popping up was telling me something wrong. Now I can’t get it to even charge enough to open the Android fix it to fix what ever is wrong with it. What can I do?