Lower back pains , intense stomach cramps , diarrhea

So Friday just passed (its now Monday here) I was exhausted and decided to have a nap on the couch . I woke up 6 hours later to really uncomfortable back pains , but I just ruled that down to bad PMS or the fact I slept on the couch for so long . Anyway , crawled off to bed and slept for a further 7 or so hours . Woke up Saturday afternoon with the same , if not worse , back pains , with additional stomach cramps (I usually never get that) and a bit dizzy but still very tired . The pain was so severe I stayed in bed all day , barely moving for anything or anyone ( I'm a 20 year old female and I love going out , so it has to be quite a fair amount of pain to hold me down on a Saturday ) . All the pains started getting worse on Sunday with the onset of the diarrhea in the early hours of the morning . Yaayyy . Remained unchanged throught Sunday aswell , I would get really strong stomach cramps before Id have to rush off to the bathroom . It is now Monday night , and all symptoms are the same , a little less frequent but still as painful . I have pretty full on studies for the next couple weeks and I need to be back at 100% asap !! Does someone have any suggestions or ANYTHING that could help ? Pllleeeaaassee . - I also havent eaten since Friday night ( I forced down some toast on Saturday and some fruit this morning so I wouldnt pass out ) but lost my appetite . - I try to put anything in my mouth , litterally makes my stomach churn almost instantly . - I can feel all the waste in my stomach/digestive tract , but I am unable to empty it out completely . - I'm trying to keep my fluids up , but still dehydrated . - starting to feel more weak than usual . - light headed at times . - I never get diarrhea , can only remember once in my life . - trying to avoid the doctor , as they usually look at me like I'm stupid then poke and prod the wrong things and give me the same box of antibiotics I have from the last 20 prescriptions of various other illness .