Rashes, Oh God No!!!!

i am extremely uspset and nervous right now. my daughter who is sick and has been in school over several years now, came home on monday saying that she was itchy. i didnt really think nothing of it, thought it was something from when she was walking home from school. and i put some regular lotion on it, we even went out for ice cream and she went to sleep later on. this morning she was okay too, just a little red in the spot that she was itching. but when i picked her up from camp (cause there was no school today, she went to camp and went to the movies, a plaster castle, and had pizza) she had a rash, at least i thought that was what it was, on her arm and it had some raised bumps on it that looked like mosquito bites. so i got her an appointment with the doctor tomorrow morning which her dad is taking her to, and she is not going to school tomorrow. it seems like it is spreading now, because she was saying that now her foot and butt are itchy too, and when i looked her butt had some bumps too, course i dont know if it is just doing that because she is itching. i am just scared now that it is going to be something contagious like chicken poxes, because i havent ever had it and it is really bad for adults. and of course my son has never had it either. so this isnt good. i am very scared about this. and also the concert that i have been looking forward to for like 2 months is on sunday, and i talked to my friend last night about it too. i finally got a hold of her after calling and texting her a total of about 4 times between both things, and she said that she is definetly still going and it is written on her calendar and everything. and that she is going to drive to my house and leave her car here, and we will go in my car. so no transportation problems like i was afraid of before. which is good. so we agreed that i would call her on friday after i got out of work to make sure of the time that she was going to be at my house, what we are wearing, and all that fun stuff. now with this, i am so nervous i really hope that whatever it is that my daughter has isnt contagious and can go away easily. i really hope that it isnt contagious because if it is, i havent had any of the contagious diseases and neither has my son, and my son is usually sneaky every night and he crawls into her bed with her and sleeps right up against her. so i am sure that he would get whatever it is really quickly. aaaghhhh, i dont need this, it is freaking me out. i am so scared that it is going to be something contagious and i am going to have a major outbreak on my hands.