During my eldest sons tween and teen years he experienced some mental health difficulties. For me it was a fine balance between knowing when something was wrong and when he was just a growing boy needing space! He could also struggle to understand and communicate his needs effectively.
 
We came up with an emoji style code, he could message me and we had something similar to this on his bedroom door too. We used this system so he could communicate and I would know whether to leave him, approach him, open a conversation/connect etc and get to know his needs as he started to consider what his needs were. 
 
But being able to be honest to my child and say, "I struggle to understand your needs sometimes/ its been a long time since I was a teenager, so this will help me be a better parent to you", was the way I discussed it, he agreed he struggles to express his needs. It's about working together to solve a problem, in our case, it was understanding each other and effective communication. This really helped us work together to keep a strong relationship. And here at Found North East we really hope it can help other families too.