Hello and Welcome to HCM, Thanks for writing to us. Pain and swilling over right flank could be muscular in origin or due to liver , ureter, intestine or renal in origin. As it is tender (painful to touch) , there is chance of infection of these. So I suggest you to get it evaluated by a physician and definitive treatment according to that. Hope this helps you. Wishing you good health... Regards. Dr Saurabh Gupta. Orthopaedic Surgeon.