Need advice

I am 46 and wondering if someone can give me some advice. About 7 years ago i had an ovarian cyst and my right ovary removed. I just had my pap in december which was normal. But now i have been getting what feels like cramping on my left side which feels like i may be getting my period, but nothing. Is it harder to go through pre-menopause with one ovary? Also my obgyn has suggested i get an ultrasound done of the left side, i guess precaution, i am kind of apprehensive, should i be?