I am so very sorry for the loss of your mother, please accept my condolences to you at this really hard time. Hard is probably no where near how you are feeling and especially seeing that you could not be with her, or the rest of your family at this time. This most certainly would have added to the pain and grief for you also. I am so sorry that this virus has taken this away from you and that you are now left with physical effects from grief.
While I am no doctor, I too have suffered physical reactions to grief, so my answer to you would be yes, the body is a very complex machine and while every one is different, we are made up of emotions that really can make a huge impact on our physical self, I have found.
Grief is a process Sparky55, there are no rules and what works for one may not work for another. It takes time and you must let yourself go through this process too. Talk, share how you are feeling, it is great to hear you have the support of your husband, this is really wonderful. I found writing so powerful in my healing. I wrote a journal and was so very raw and honest, I blamed, I said some horrible things but it was for noone else to read, just me. I also credit this forum, to the wonderful people who shared their stories of healing and the things they did. My grief was related to suicide so I was able to learn some things too, that allowed me to stop blaming myself which was very important.
It is totally fine to cancel meetings, to avoid life for awhile, to cry and to do all the things you feel you need to, infact it is important to allow yourself to feel and do these things, what happens next is also important, that you don't take up residence in this space. That you do some things that make you feel good, that make you smile and also know that you are allowed to feel good too. Also accepting that one day you may feel quite ok and the next day like a wreck, this is all part of the process I have found.
There are some wonderful services available too if you need to talk to a person, even your GP if you find you are really struggling, infact if the gastro continues too long I would get a check up on that one too. There are some amazing people on the Beyond Blue phone support line on 1300 22 4636 as well as even LifeLine 13 11 14, please reach out if you need an ear.
We are here to support you also and I am so proud you have reached out, be kind to you, you are going through a rough time.
Hugs and chat soon