Battery percentage going down but its charging
my samsung recently started not charging properly. It is plugged into charge but as i use it the percentage decreases until it goes to 0 and shuts down. i left it in last night to see if the problem was me using it while it was in charger ( even though iv never had a problem with this before) and it only had 83% when i woke up. so i left it in for another hour and it was still on 83, i jiggled the charger then it started charging. What is wrong with my phone, is it the battery or charger.
Phone is fairly new ( 6 months)
Charger is original
Samsung Galaxy S3 Neo