What Causes Nausea,back Pain And Excess Salivation?

hi im 42 year old I have my tubes tied 13 years ago I took two pregnant test came out negative I get my regular period and for over a month im getting nasua back pain my mouth full of saliva I feel something on my left side of ovary no pain at all I saw my oBg they did a urine test came out negative I haven't done the blood test but don't know what to think