Hi, Thanks for using HCM.
After hit in chest difficult to move left arm in some positions, unable to pick up heavy loads feeling pain when breath in, skin moveing in and out when breathing suggests thay you have displaced shoulder or injured any muscle and there may be some rib injury
also. Skin moving with respiration suggests injury to lung. You need to restrict movement now, get xray of shoulder joint and chest and consult your doctor for examination and management ASAP.
Hope I answered your question. Feel free to ask me if you have any further queries.
Wish you good health. Take care.