Hi MKC and welcome.
I am so sorry that you are living with this level of fear right now. I believe that a lot of parents have health anxiety that may stem from the enormous responsibility of taking care of little ones...and the fact that we have to stay well and alive to see them through to their adulthood!
Many of us here do deal with the same fears and symptoms that you describe. As Larry suggested, reading other's experiences can help you. If you choose to do a search (blue button, top right side of tool bar) you can find many threads on the subject of health anxiety/fear of dying. You may be comforted by knowing just how prevalent this is. You may also get some good ideas on how to help yourself through this tough time.
I can also make some book recommendations for you at your request. There are some good self-help books that deal with the specifics of health anxiety/fear of disease.
I always recommend talking with your doctor about other treatment options as well...whether is means trying a new med, and/or getting a therapy referral.
I hope that you will continue to post with us . We are always here to encourage, understand and support eachother...and we are always glad to welcome a new member!:)
Talk to you soon,
Scaredy Cat