This phase I/II trial studies the side effects and best dose of R-(-)-gossypol acetic acid when given together with lenalidomide and dexamethasone and to see how well it works in treating patients with multiple myeloma, also known as plasma cell myeloma, that has come back after a period of improvement or has gotten worse after treatment. R-(-)-gossypol acetic acid may stop the growth of cancer cells by recognizing certain proteins and stimulating programmed cell death. Lenalidomide may stimulate or suppress the immune system in different ways and stop cancer cells from growing. Drugs used in chemotherapy, such as dexamethasone, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving R-(-)-gossypol acetic acid with lenalidomide and dexamethasone may work better in treating patients with multiple myeloma.