I had swollen testicles yesterday and they had a dull pain and now that seems to have gone, away, now the pain has moved upwards into my upper groin?

Testicular Troubles: Transient testicular swelling may be due to an infection, viral or bacterial. Many times there is no urethral component (i.e. Discharge). Fever may or may not be present. One sided swelling is typically seen in trauma, torsion (sudden twisting of the testicle on its cord), or vascular injury. The epididymis is also a possible culprit. The ache may indicate a progressive problem; get examined.

See doctor: You may have epididymitis or some other inflammatory condition of your sperm-producing system. This might be sexually transmitted disease, or possibly just an obstructive disorder. In either event, seeing a good urologist (and most are excellent) would be beneficial.