Thank you for your answer Hazyjane. You have been really supportive and I appreciated that. But what I would like to know in particular is if is really possible to apply for a PhD position being already a PhD student in the same uni..It would be much easier for me to take a decision having two available options in my hand. I don't want to put at risk my actual position by applying for another and, at the same time, I don't want to miss a potential great opportunity because of this fear. Any help?
Thanks,
John.

Hi there,
I'm new in this forum but I used it in the past to get very useful info. My question is: Is possible, without any risk, to apply for a PhD position being already a PhD student (in a different department) in the same uni? I'm currently doing a PhD and sadly I'm not enjoying it at all, I'm doing this PhD in a different subject from what I studied in my master. In the beginning I applied for this position because it was not clearly specified any detail regarding the research project and at that time it seemed to me a reasonable opportunity. Unfortunately when I started I realized that what I was supposed to do was something completely unknown to me. The supervisor keeps on saying that I'm doing fine but that is not enough for me to go on. Recently I found really interesting PhD opportunities in the subject I graduated in, the issue is that the position are within the same university I'm working now. I would really like to apply for them but I don't want to leave my current PhD before (or to risk to be kicked out!) being chosen for the new one.
How can I do? Have you ever been or heard about of such a situation? Help me please.
John.