Upon exam, by chance the doc noted my spleen was swollen. bloodwork showed nothing abnormal. what could cause random swelling? need for further tests?

Many reasons: 1. Exam could have been mistaken. 2. There are numerous causes of increased spleen size, such as alcohol induced liver disease; other liver diseases that cause cirrhosis such as hepatitis b or c; lymphomas; splenic malignancies; vascular diseases; amyloidosis. Symptoms like these are best evaluated in person by your physician. Based on the findings, a treatment plan can be developed to help you.