Firstly, I am sorry to hear about your brother, I hope he is doing ok at the moment.
I am sorry to hear that you are dealing with MS anxiety and some symptoms too. I actually have a very similar symptom at the moment with my left leg feeling kinda numb, cold and tingly. I have had this in other limbs from time to time too. It has always gone away, but of course, now I am very focused on my leg and how it feels. I actually had a brain MRI about 8 or 9 months ago and the results were clear; no signs of MS or brain tumour. Of course, now I am worrying that something could have changed since then. But, realistically, I know that this is very unlikely. I have dealt with other aches and pains, and tingling over the past few months too. I have to conclude that it's anxiety, but it is naturally difficult to accept. It appears to be true that focusing on a symptom magnifies it. My advice is to try to accept what you are feeling but not to think of it negatively, just to accept that your leg feels weird but that it means nothing. It should hopefully go away then.