When emotions are catching up on you, always try to view on the bigger picture. Remind yourself of the reasons why you invested into something, why you bought that stock, why you put your money in it. Remember all the factors that made you think that your decision was correct. Check if your your targets are still on view. Consider your time table. If majority of these parameters are still in parallel of what's happening now, then you don't have to worry that much. Breathe. Just keep a watchful eye.
But if you can't articulate any of the considerations above, it might mean that you didn't really put a lot of thinking before acting on your investments.Then you have all the reasons to be that nervous. But it's not too late. You still have time to change track and make better choices in the future. Learning thru experience still gives the best lessons. There's always the time to bounce (pun intended).