Hello I Am A 15 Year Old Guy Who Currently

Hello I am a 15 year old guy who currently weighs around 57 kg, before i was 60kg. My aunty gave me these diet coffee sachets 4 days ago and i drank them for three straight days and afraid i have dehydration. First symptom was a migraine like headache in and between my eyebrows, ache from my jaw to behind my ear. Then my neck became stiff and so i drank water with 1/2 tsp of salt and 6 tsp of sugar and went to sleep. I only slept for a few hours before i woke up thirsty again and this time i was dizzy when i stood up after drinking water and having to urinate. My urine was between clear and pale yellow but when i wiped there was a very small streak of blood on the tissue paper, i also have a dry throat, sore ear and runny nose and i keep having the urge to cry-in which i actually do cry. Please help! Thanks!