I'm from Ethiopia, and I completed my PhD degree in mathematics three months ago. Now I'm working in one of Ethiopian universities as a mathematics teacher. Unfortunately, I'm not satisfied with my current position and did not enjoy the work that I did in my PhD study. So I'm looking for another PhD (in Mathematics) in Europe or Canada. Is it possible to apply for a second PhD? How can I convince a professor to get his consent?
There are some places that would forbid this and others probably permit it. But there are better options, such as a post-doc or even a paid faculty position somewhere. Earning another degree won't do anything for you that further study won't. But you can get that study while working, even in your current position.
What you really need is a relationship with one or more other professors in your field with whom you can work and extend your knowledge. You want colleagues, not supervisors. International cooperation is even possible these days if travel is difficult.
But two PhDs in the same field seems to me, at least, to be spinning your wheels.