After several months of constant pain in my back, I finally decided to get scans made of my spine. Turns out I have a double lumbar disc hernia (L4-L5 left and L5-S1 right). Luckily they are minor, so there not even talk of needing an operation.
For the hernias to go away, I need to rest. I'm supposed to lie flat on my back all the time with my legs folded in an angle. This should reduce the tension in my back and allow it to cure by itself. This position makes it however very difficult - almost impossible - to program while holding a laptop. I searched the web for appropriate laptop stands and stumbled into 'The Lappyvator', a build-it-yourself project that is easy to execute. The only downside seems to me that your arms are in a vertical position and don't rest on anything at all, which is bound to be very tiring. Luckily, I use the AlphaGrip as my keyboard, so I don't need to touch the laptop, eliminating this problem.
Now I'm able to work regular hours and totally rest my back. I haven't tried it yet, but it also seems like an awesome approach to watch movies or series in bed with the laptop.
Below are the pictures of my own lappyvator. I've built it so that I can easily remove the horizontal feet and take it with my in a suitcase when I travel: at last comfortable computing in hotel rooms!