daughter has issues..sensitive child syndrome?

[1pj]

Hi Ladies,im at my wits end here and dont know what to do,i don't know whether to get my daughter checked or not,i feel I need advice and don't know where to go,its about my DD who will be 5 in febuary,shes always been a handful and lately im at my wits end,i feel so bad because I feel all I ever do is am grumpywith her or telling her off or getting stressed out!So when I say handful I don't mean naughty really,she has strange habits,or behaviour,she simply does not stop,for example with questions,she keeps asking questions constantly and I don't just mean why is the sky blue...really intense questions and constantly its driving me crazy,mum whats that man doing,mum why is he doing that?and keeps tapping me on the shoulder mum mum mum, sometimes the same question over even though ive answered her constantly and if I don't answer her(which after 40 questions in 2 minutes I sometimes nearly meltdown)she goes crazy crying and melt down,shes so sensitive to pretty much everything,noise,peoples feelings,lights,just EVERYTHING!she crys all the time about nothing,she sometimes aks her brother if hes her friend(hes nearly 2 and a half)over and over then crys if he says no(being silly)she keeps asking me things over and over mum can I have a drink ill be making it and shes still asked another 50 times mum are you making my drink??I don't know if shes unsure of herself or needy and sensitive or just plain demanding?i don't know how to handle the things anymore sometimes I feel shes doing things to make me loose it and sometimes its like she genuinely does it and then crys,its so hard to deal with it out too as people just looks when shes crying all the time and then my friends cant understand and some think shes just an awful child,i just don't know what to do any advice would be so much appreciated has anyone had anything like this?a few people suggested she might have scs sensitive child syndrome?but I just don't know where to start do I just take her to a normal doctor?