DD aged 13 had a falling out with her friends just before Christmas and is very unhappy. I'd put it all down to this but I'm wondering if it's part of a bigger picture and when I should try and get help.
I'll try to be brief, sorry if it goes on.
She's always found making friends very difficult. I mean even as far back as reception I'd be told she prefers to play alone. This seemed to settle in years 1-4 but year 5 was a bit tricky. Then year 6 was awful when she had no friends and was totally isolated. I'd thought this was due to her friends leaving and the other children being in established groups. I hoped year 7 would be a fresh start and it was when she made a really close friend. Her only ever best friend according to her. Unfortunately the friend moved countries at the end of year 7. 
She got in with this new group at the start of year 8 and I breathed a sigh of relief. However, during this time since September she's also changed quite a bit. She's been reluctant to go to school (but has done, just moans alot), very difficult when doing homework which she leaves to the last minute, her grades have dropped, she comes in and goes straight up stairs saying she's had enough of people. She spends alot of time on her phone and upstairs and is pretty vile to her younger siblings who she'd previously got on well with. Dd is my eldest so I thought it was just the teen years and kept telling myself the MN mantra: this too shall pass.
However, last night I found a page on Instagram she's following which was all about sadness. I asked her if she felt that way and she said all of the following : she hates school, the noise, the pressure, the people. She finds making friends very difficult and doesn't get people, she said the group of girls I thought she was friends with were mean and excluding her. She has excluded herself further by sending them all a message saying she's down with them and now they've blocked her on SM. I tried to tell her it probably would have passed and there was no need for the message but she just says they're mean and she'd rather be alone. She may be right but I can't help but think why her again?!?!
She also said she feels sad, depressed, anxious. She feels panic when the teachers go too far ahead and she says she can't keep up and there's no time to catch up.
She repeatedly says eh doesn't like school but when I ask exactly what she doesn't like about it she just keeps saying "I don't know".
I'm not sure what to do to help. I am hoping the argument with the girls will blow over but even if it does, I do feel there maybe more to this. Her issues around friends seem so deep. DH thinks she needs to lighten up and stop being so serious. She's always been a very deep person. Lots of deep emotions and over analysing going on. Is this all normal or am I missing something more serious? I am thinking anxiety or maybe even ASD at the lower end of the spectrum?
I have planned to put a different routine in as she definitley doesn't sleep enough, help her more with organising homework as she tends to just give up if she thinks she won't do well which she won't do as she leaves it all to the last minute 
. And get her off her phone and out. I also want to try and persuade her to contact one of the girls from the group to break the ice before she goes back. If that doesn't improve things by half term I might involve the school. Just not sure what else to do.