Slight nausea , fatigue , headaches

I have been experiencing these symptoms for the last month or so. Sometimes slight nausea or nausea in response to smells. I am constantly feeling tired and sometimes my joints ache. I get headaches. I also have a decrease in appetite. I have had several negative pregnancy tests but do breast feed. Anyone have any ideas on how to resolve this or if its a medical problem? I don't have insurance so I really want to avoid going to the dr if I can.