Severe Cramps

I have the worst pain ever and I know for a fact it's not my period because that only just finished like a week and a half ago. My eating has been off too due to these cramps and I don't know what it is. I'm nauseas too. Does anyone know what this might be? I'm not able to get in to see a doctor til late next week as they're booked and I don't like going to other medical centres. These cramps are killing me :(