Symptoms of mononucleosis usually are most intense during the first two to four weeks of the illness, but, they can last as long as several months period (in small percent of patients symptoms can be present at one year after illness has started)
Young people like you have more reactive lymph nodes, meaning that even the infection has been resolved, lymph nodes can still stay swollen for a longer period.
Chest pains, cough, shortness of breath are less frequently occurring symptoms and signs of mononucleosis.
Do you feel the abdominal pain like discomfort or pressure-like in your upper left abdominal quadrant?