What Causes Prolongled Soreness In Ribs Under Left Arm?

I have sore rib under left arm for about six months. Iphone only comes if I putting on a coat or slouching in a sofa. I have t sit up straight. Kit is like hitting you rib against corner of table. I had lymphoma on spleen but checked last week and blood ok and no lymph nodes under arms necke groin. What would cause this soreness. Woul x Ray show it up I had Cat Scan for Lower tummy and chest x Ray. Found I had sciatica in left leg coming from lower back.nopain now gone