What is the best way ti figure out what these lumps are in my lower back close to my spine and on top of my siatic system e.g mri w/contrast, x-ray...?

Start with physician: Start with a visit to your physician for a complete history and physical. If your physician cannot make the diagnosis in the office, imaging may be appropriate. Spine radiographs would likely be of little use. Mri with contrast to include the area of concern would likely be the best 1st test. If cortical bone involvement is suspected, none contrast ct scan may be indicated as well.