Weren't you advised to see the doctor after a week?
Hello and hope you are doing well.
The bruise in the groin could be due to superficial thrombophlebitis, when a superficial vein becomes inflamed and a blood clot forms within the vein, commonly due to an injury like an injection into the vein. The swelling and redness may sometimes spread along the entire length of the infected vein. For this, elevate the legs while sitting and sleeping and place warm compress over the affected area. OTC Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, will help with the pain. However, if your symptoms are worsening, consult your doctor to rule out an infection.
Hope this helped and do keep us posted.