Pain, Pain Everywhere

Everyone knows that if you are picking up a large object you should use your leg strength and not your back. If you bend over multiple times during daily activity you should bend a the knees and not bend with your back. In my job I lift heavy objects and bend over all the time. I have had back pain for awhile. So, I started to take this advice not wanting the back pain to get worse.. Well, now my knees are in excruciating pain. After I bend at the knee when I try to get back up I have to hold on to something. If I don't my knee hurt to much to give me the strength to raise myself up. I am getting old. If it's not one thing it is something else.