I had LL pain? sciatica and had MRI lumbar spine done which showed

multiple level disc dessication with possible L5/SI thecal sac compression. My question is - is my conditions very serious? What should do, and recently I had pain on my right leg and which travel to my buttock and I cannot differentiate where does the pain actually come from. My left arm and shoulder also get pain. Does all these pain connected with the spine. Please advise me what I should do. Thank you.