I can totally empathise Bhj as I had a similar DD a couple of years ago, she's 15 now and somewhat better than she was, thank goodness (so I am hopeful there is light at the end of the tunnel for you!).
Firstly I would tell her she can always come and talk to you, obviously she preferred texting at the time, as long as she can communicate her feelings any way she can. Good idea to take her to the doctors, I hope by now you have got some good advice there.
Just wondering if it could be linked to her hormones, I think a lot of it was with my DD, I gave her some Complete Woman capsules to help as she is also a vegetarian and needed iron. I should say that possibly the only reason that I didn't go to GP is that I am a nurse and there is a doctor in the family so I think I relied on our own medical knowledge (not saying that's a good idea necessarily). Is she getting a decent diet and good sleep? And wondering how school life is in general, I think as regards the drama etc a lot of teens would find these subjects worrying, many of them do not like being on show at this age. I remember I really hated having to read out loud, esp at the front of the class and this lasted til I was in my early 20s! Would it be worth having a word with school if there is anything concerning her there?
Re the embarrassment, my DD used to get crippling embarrassment and would not do the simplest of things eg like pay for things at a shop, she is still that way to some degree but a lot better so I would suggest just a normal stage. I tried to encourage her as much as possible and told her that other people are not watching and judging her all the time but it is difficult to get this message across. Sometimes I got a bit tough and would not do the things for her that she couldn't do, if she didn't do it , she didn't get what she wanted.
If possible, I would suggest some fun things with you or any other family you have as much as possible. Just think of things to get her out of her room, anything, give her little jobs to do to help you. Will she come and watch a film or comedy with you and play a board game? it is important to have some time together to get her mind off her worries. It helped my DDs confidence to join a martial arts club so perhaps look into some sort of activity/hobby.
Hope I have not gone on too much, please PM me if you wish and take care. Hope you feel better today. 