Good suggestions here..I have some of the same problems and my doctor told me walking (flat surface) and stretching is the best. I recently added the core balance ball and light weights to my routine. Taking it slow at first. I started out only being able to do 5 minutes on treadmill and I'm now up to 30 minutes. I was taught how to use the ball and to stretch correctly in physical therapy though. You might check that out if possible. Sciatica, back and neck pain are real obstacles for me..just have to take it a day at a time and not give up.Ice helps me more than heat.There are a lot of good health and wellness advisers here . I would check with them. I just wanted you to know that I understand.
Hope this helps in some small way..I know it's tough to keep going when you are in pain. I just keep doing SOMETHING every day.