blond3 welcome to the forum.
This place is full of kind ,compassionate and supportive persons.
I am sorry about your brother and I can not begin to imagine the depth of your grief and loss.
Grief has a way of presenting itself in different ways and your body is showing how is it responding.
Have you thought about contacting a grief support group as talking to others who understand why you have been through can help.
You can browse through the thread or search topics about grief in the search engine.
It has only been a few months and you need to give yourself time and just grieve in your own way and do what will help you through this hard time.
I just wanted to welcome you to the forum.
I have suffered grief but not of a sibling .