Hi. Thanks for your query and an elucidate history. The best and the simplest way is to get an FNAC=fine needle aspiration cytology done to determine the cause. MRI would have been a better investigation as it would have shown the position of the discs , any compression on the spinal cord, nature of the lumps you are noticing and all relevant information even about the brain as you have headache also. If the lumps are not attached to any important structures , better to get them removed and subjected to histology. This may end all other problems.