bach543,
You have hit several critical stressors which can, alone, cause health problems for people with MS.
Oral counseling can help, even a pet like a cat, dog, or other can also help. A dog, for example, can do more in an hour than 2 weeks of meds for depression.
You have many triggers happening in succession.
1. You have MS, you will have MS for the foreseeable future as it is a chronic disease. You will not go back to a "normal" pre-MS life. Reset your definition of "normal" and move on with your life.
2. Loss of a job due to MS? Disability might be needed even if it is for a short term. After two years away from my career, I was ready to work, but my doctor knew better. I am better for having taken disability because it removed a great deal of stress from my life.
3. Your mother is not going to get better. If there is a hospice or some kind of care giving available, please use it. I spent a year with my mom after her car was hit, causing her Parkinson to progress more rapidly. I was in terrible health trying to help her. I had some family members try to help too, but the care giving is highly stressful. MSers do not always have the capacity to maintain care giving due to our own weakened state. You want to care for those you love, but the facts are that we might be limited in that ability.
All three of the issues you are experiencing have resolutions. All three are quite likely responsible or partially responsible for your current situation. You can lessen the impact of these trigger events and regain some health. These triggers may simply be too much for med, therapy, and exercise to overcome. If you can lessen the impact, you might find that the meds and exercise become more effective. If an exercise is not working, try a different one.
Please know that we are here for you. Please feel free to openly talk about what is happening because this sharing and talking can be therapeutic. You can get better. I believe it!

We need to find you a regiment that works for you.