Lower abdomen. Weights? any other test?

In 2011 I had got hit on the Lower right abdomen while in a car in the US. A urine test was done and it was normal. The pain gradually went away. Two years later I was lifting 7.5 kg and got a strain in the same area (lower right abdomen, groin) which continued on for a long time and prevented me from doing any activities. I got a ultrasound which didn't indicate anything abnormal. A physiotherapist in the US gave me a few stretches and strength exercises which helped me. These days when I lift something heavy I often get a weird feeling in that area. Slight pain but mostly a feeling of being heavy. I then stretch which helps me but I would like the problem to go away completely. It keeps on reoccurring which prevents me from doing many physical activities. 1. What can I do? Any recommended stretches or strengthening? 2. What can I do to improve healing of that area? 3. Is cardio on the elliptical or treadmill fine? How about light weights? 4. 2013 ultrasound fine. any other test?