After my period I have a yellowish discharge. Does this mean an infection? No other symptoms. I am 45 years old

Possibly. The end of a menstrual period can be mostly serous fluid without red blood cells and this can have a yellowish appearance. Yellow can also be a sign of white blood cells which would indicate an infection. Bacterial vaginosis is another discharge that is sometimes described as yellowish and is commonly seen right after a menstrual period. A gynecologist should be able to distinguish the cause.