S3 charging Very slow

So recently my Samsung galaxy S3 phone stopped charging like it used to. While I'm using it. The charge goes down. And charges super slow when not using. Charged all night and goes up by about 50%
This only starting happening a few days ago. I switched batterys and charger and still same thing happening.
There's this app where you can check your charging current. For me it shows charging at 100mA. Is this normal? My phone is rooted by the way and has custom ROM. Lollipop 5.1