My 18 year old Son is at Uni in Liverpool but he comes home every weekend - he's close to his group of friends and they go out every weekend - not drinking - they're all very keen on their cars and are out driving a lot. We've always had a really good relationship and can talk about most things but I'm getting really worried about him. He's not been back to uni for the last couple of weeks, constantly telling us he's going later that day, but as I say - he's not gone. He is keeping himself very much to himself when at home, shut away in his room and he won't speak really when his Dad or I go in. There's very often a smell of cannabis coming from his room but he swears blind he's not using anything and it's just our imagination. Today when my husband went in his room, there was a spliff on the floor. His attitude has plummeted over the last couple of weeks and he was so rude on Saturday I told him to go - I packed all his stuff up and told him to go and stay with a friend as we'd had enough - at no point did he apologise or seem in the slightest bit concerned, and just arrogantly said he wasn't going anywhere... he didn't go and I'm glad but his behaviour and attitude hasn't changed and today, he's been going to get a train to Liverpool at various points all day but he's still here and won't speak. We are worried and at our wits end - if you have any advice to offer, we'd be really grateful