Can I take something else in between? Can I put on some heat?

Hello, for a few days I have had a lot of pain in my lower back and on the side of my left buttock. Difficulty to sit down. Difficulty to move. When I stay too long in a position I have difficulty moving without being in great pain. I changed my computer chair and since then I have had small pains. Then I made a wrong move at the gym and it got worse with the situation described above. I'm already going to physio for a shoulder problem and my next appointment is on September 27th. I'm taking a celebrex in the morning and evening, but I'm still in a lot of pain. I'm getting rubbed.