Struggling player really needs help

So I've been in a slump for about six months. I can play custom games with my team and do amazing versus them, but I get on ladder and well I'm like 2/20 already this season. I've never had it this bad, I was high platinum and playing Diamonds and Masters prior to my slump and going strong, and now I can't even beat silvers. Does anyone have any experience dealing with this and can they offer any help at all? Please