Support? Yes...compression shorts
4 months is definitely enough time for a 'groin pull' to heal, if you've laid low on the exercises and just did therapeutic twists and turns to strengthen the surrounding area.
Does one of your testicles hurt more than the other? If so, you could have an incipient hernia with accompanying nerve compression in the inguinal canal.
There are 3 major nerve branches that run through that area. A disruption in any one of these can cause diffuse and localized pain in the lower abdominal/groin area.
Suggestion - make sure your ultrasound is being performed by a radiologist who knows about these type of hernias and how to spot them - and NOT by a technician.
Here is an article that even shows you how to hold the transducer when performing this type of scan. Also, it needs to be a dynamic ultrasound where they are scanning you both lying down and standing up.
www (dot) sportsmedicineimaging (dot) com (slash) Sports_hernia (dot) html