What Is The Treatment For Pain After Lifting Heavy Box?

I am 76 years of age and in general good health though possibly a little overweight.
It was necessary ro me to assist a delivery man who was the other side of a wall that came up to the higher part of my chest and, bear in mind that he was lower than the patio I was standing on. He lifted up a fairly large box containing whicker furniture an it was my task to reach down and try to assist this effort by getting a purchase on the sides of a box which contained no protrusions that I could get any grip on. I brought out a chair to enable me to reach down further with the ultimate objective of assisting the movement upward of the box until between both our efforts we could tilt the box onto the top of the wall and I could then get a proper grip. In so doing my right rib cage (side) came in contact with the sharp edge of the wall not from any fall or with any force but merely contact. I immediately felt a sharp pain and had to withdraw my assistance for the moment. Still feeling a pain I resumed the operation, this time avoiding further contact with the sharp top of the wall. I have since suffered a consistent pain when bending, walking, lifting anything off the floor, coughing deep breathing and the like and the like. The pain is not so bad that I can't cope with it but is lingering with only my imagination trying to convince me that it is lessening. I suffered this on Tuesday 7 Jan and an inconvenient pain continues. I'd like reassurance that it is perhaps only ligaments or some such matter that will gradually get better?