What Causes Spotting, Stomach And Lower Back Pain With Bloating?

good morning, my name is johanna, im a 34 year old female, I had an ectopic pregnancy back in july and my right ovary and tube were removed, Im not trying to have a baby in fact i have been on birth control since I had the surgery and i had my period in august twice on the 5th and the 13th. but this month i only bled a little bit on the 15th and it stopped, i have a pain on the left side of my stomach and my lower back, also a lot of bloating ....should i be worried ?? i feel like i should have a sonogram just to make sure everything its ok !! please help!!! thanks johanna