A ilness and im loosing hair and feel so alone and depressed:(

I'm 15..this shouldnt be happning:( In junary i was given getting aload of symptons and basically i have something worng with me and the doctors dont know what yet!! im just finding my symptons like i have breathing problems,walking probelms,hands start shaking etc.etc. I've never been a happy person..ive never had a boy i love.. i've never been good at school and ive never had 'all the friends' im really ugly and my hair is what makes me ok and i can't get my hair out my mind..i dont backcomb it or anything i use thickening shampoo and it was great but mum says stop..so i did. and now my hairs thin around the sides,, if i loose my hair i don't know where i'd be in the world!! i'm so worried i'm even crying! my mum says i have thick hair. i used to but now anymore i used to backcomb it and not brush it but now and since septemeber i have tryed my best to look after it.. if my mum brushes my hair and a hair falls out i go mental and she knows i do... she knows i wouldnt live without it.. i'm havingtests done soon for my illness.... loads of different sorts.. i havent been to school in 2/3 months because of this illness which is to do with my ammune system i think! i just need to know what to do because its the only thing that i cant live without,. ovbiously im depressed i cant live the house atoll and depressed about like boys and stuff which is normal i think but seriously i'm pariniod and i dont know if i am....but also my scalp hurts:'( i just need some advice and it may possibly be a symptons but i cant live witout my hair!! Why me:'(:'( please someone help me xxxx