Why does my SamSung Galaxy S3 charge slow but drain fast????

[AC Question]

I have had my S3 for about 4-5 months. When I first got it the phone worked great but about a month or two in the camera started glitching but after a few weeks to a month it fixed its self and has been working good. Though about 3 days ago I noticed it took my phone 4 hours to go from 30% to 50% with the original usb cable plugged into the wall, I then got an extra Samsung usb cable and charged my phone with it also from the wall. It took 7 hours but finally made it to 100% I then unplugged it and I used it for 30min I sent 4 short texts and I played one Yahtzee game on it. My battery was at 40% so I plugged it in and turned my phone off for 4 hours when I came back it was at 80% so I left it on but on standby and it went to 82% in 1 hour. I took my battery out for 15min and in 5 min of it on standby it went down 10% so I took my SD card out and turned my phone back on and have left it out for 40min now. I plugged my phone back in as soon as it turned back on and it went from 72-84% in 5min, I thought it was fixed so I unplugged it that way I could use my phone but in less than 15min I sent 12 small texts and been putting my s3 on standby between texts like I always. But I just noticed it went from 84-61% in just 15min so I plugged it back in and put it on standby for 10 min and it was at 84% its now been plugged in on standby for 10 min and its still at 84%. I have battery doctor and optimize my battery(two apps from google play) on my phone and they don't seam to be helping. What do I do??????????????