It is my fifth year of graduate studies in chemistry. I haven't had enough training from my professor and I don't have enough confidence to do even a post-doc. It is so close to my graduation, that I deeply feel that my PhD is nothing. So, you can imagine how stressful could be my life. After thinking a lot, I decided to do a second PhD in not chemistry but in biomedical sciences. I found a professor in one of the med schools and he told me I could be his graduate student next fall( since there is no chance for applying for spring) and during spring I can be a research assistant in his lab and work there for around 7 months until I will get the admission. I asked one of the faculty members and not my PI to help me make the best decision. He recommends me not do that and apply for a pos-doctoral instead. I am so confused. I really feel that I need this second PhD, but people are telling me to not do it and find a postdoc position instead. Could please help me?
Academia is a path of constant learning. If you want to change field, a postdoc is a great way to do that. You can even change back after, or combine the two fields. So long as you can pass your PhD then it has served its purpose. Just make sure to advocate for yourself in the future to get the training and support you need.
The same thing happened to me. I was not being trained by my first advisor. It was not impostor syndrome, I was just being treated like a cheap lab tech. There was no "advocating for myself" way to solve the problem: that advisor was unable and unwilling to train. Nice guy, but useless.
Near the end of my PhD, I asked for a Master's degree and applied to another PhD program in a much better school. Pretty much submitted the PhD thesis as a master's thesis. At the new school I got the training that I wanted, and because I had so much lab experience, was able to finish the PhD quickly.
I went on to a successful academic career.
Speak with other professors, look into other programs. Leave with a Master's or not. Get the training you need.
Regardless of the actual situation that would lead to your decision to pursue a second PhD, I guarantee you that it would be a huge red flag in your curriculum vitae. Since you are so close to completing your PhD, I recommend following through and then moving on in a postdoc that best suits your interest and career goal.