The symptoms you reported (pain in left abdomen, menstrual period late for ten days, nausea after meal) are not sufficiently specific for any definitive diagnosis to be given.
However, you might be experiencing an issue related to your left ovary. For example, an ovarian cyst which affects the production of the female hormones might cause the pain by putting pressure on the surrounding tissue. The late menstrual period might also be explained by the same hormonal imbalance caused by the ovarian cyst.
However, there might be other causes for the left abdominal pain and the late menstrual period. So, you might want to visit your gynecologist for a physical examination, laboratory female sex hormones tests, and an ultrasound scan which might be able to help in visualizing the cyst or other causes for the reported symptoms.