This sounds exactly like me 2 years ago. I think it's a mix of anxiety and depression. the stiffness of the neck and difficulty talking in social circles is connected to the anxiety (most ppl who suffer bulimia tend to have bad anxiety and we care too much about what ppl think of us or how we look) and the constant tiredness and exhaustion is connected to the depression.
what i did is that I started going to my campuses counselor and started venting about everything. I also started forcing myself to hang out with friends even if i felt terribly awkward. I also started walking outside without any long shirts or jackets trying to cover myself (i was super thin but thought I was obese or deformed for YEARS). i did all this until it became second nature. you need to trick your brain into thinking you are ok. of course it is still a daily battle but i am sure you can do it! also this is just my experience so yours could be really different. i'd advise you to speak to a therapist or someone who can help you. i love you sistren and i know you can bounce back
