I feel very nauseous and I have mild dizziness, also I have low blood pressure. Nausea not fever. Back pain along with dizziness, cramps in the lower abdomen and also a slight headache?

It is time to ask for visit to the doctor. There's nothing I can do or say online, apart from what you already know about drinking plenty of fluids. You described his lower blood pressure , so I guess that means less than normal value . This is worrying and could be dangerous sepsis and infection can not reach the bloodstream. Fortunately , you do not have a fever , so maybe your blood pressure is lower than normal because it has not been drinking enough liquid so it could be dehydrated ( could also explain the headache ) . Back pain can be from a kidney infection or stone , to a abdominal pain appendicitis. If you are a woman ( I did not see any high benchmark for its genre ) , the ovary can turn on itself or could have a big cyst. In any case , you need immediate medical attention . Good Luck!