left little toe going numb after sitting for 30 minutes

Hi there. For the last 6 months I have been experiencing an area of numbness around the whole of my left little toe and possibly part of the toe next to it also. This only seems to happen when I have been sat for 20-30 minutes and then disappears within 5 minutes of standing up. Im 40 years of age and of slim / athletic build. I also experience sciatica in the buttocks on both sides after sitting for 30-45 minutes and have had this for about 6 years. Many thanks

Sounds like it could be piriformis syndrome, but it'll require a proper assessment to know for sure.
For self help, goto youtube and search "piriformis stretching and "piriformis massage". you'll probably need someone to help you massage effectively. Try those, see if that's all you need, sometimes it's that simple.