My dad has pain in rhomboid area.2 months and there is small swelling. pain worse.at night? what can this be?

Muscle spasm: I often see spasms in one rhomboid. Stretching, massage, nsaids, ice or heat can all help. Stretching has the best chance of helping. The shoulders and cervical spine all need stretching and relaxing. He can use his own hand for massage. Getting frequent short massages from a family member is ideal (like 3 minutes twice a day). Deep relaxation breathing release shoulder and neck tightness.

Rhomboid tendonitis: It is very likely rhomboid tendonitis, which would call for rest from activities that worsen, then antiinflamitiry medication and strecthing program, if not getting better should be checked by md, to assure some other soft tissue problem is not coexisting, if history of weight loss, would screen for sof tissue neoplasm or lymphoma, although much more rare.