Rib feeling

Hi! Has anyone ever felt like they were very aware of their lower right rib cage? Its not painful but if you stretch your arms up or do something its as if something is pressing on the lower part of your rib cage?? I gues you can say its a feeling of “fullness” there with some dull pains a little bit down in the upper right part of your stomach. Im 18 and have had this feeling for like 5-7 days. My period was very late and i also keep getting tension headaches on my right side. It couldn’t be anything serious right?