Welcome to the forum I saw from your other post that you are recently diagnosed and on Rebif. I hope that you do well on the Rebif and not having many problems with it. We have a lot of really wonderful people here and I do look forward to getting to know you better!
I think that when you are dealing with a chronic illness and all the symptoms that come with it, you are definately apt to become less tolerant to things that didn't use to bother you. Just dealing with the symptoms themselves is hard, and sometimes even the littlest thing added just makes it too much and you can blow. It might take some time to adjust to how you feel each day and know when its time to just take a break for yourself.
You sure have a lot on your plate working full time, getting your degree and dealing with MS too. I'm sorry you have to deal with all this at such a young age though, you said 24? Keep at it best you can, but at the same time try not to push too much.
Take care, we'd love to hear more from you.