I am so sorry about your nephew dying and your sister must be devestated. I lost a son who was 21 years old and I know her pain first hand. My prayers are with her.
There are so many sx of anxiety and if you have had this before and it went away it may be your anxiety. If you are looking for positive reassurance if it is your anxiety, it would not hurt to make an appointment with your PCP.
Take care and keep posting.HugsKitt