How can I keep my mind focused when grieving?

I know this has been asked before but I want to link this to my personal situation. Sorry to do this!
Ok so I have been finding it impossible to concentrate on anything. In October a friend of mine died in a hang gliding accident, he had been travelling for the past 2 years and I hadn’t seen him for ages but spoke on facebook often, he was 25. On the 23rd of this month another good mate of mine died, he slipped into the river on his way back from a party, he was 22. I am in the middle of doing my masters and have lots of exams and coursework I have to do. I do not have time to stop. I took a few days off over Christmas and after I found out about my most recent friend’s death but I just havent been able to concentrate on anything. My eyes just glaze over. I am usually not the greatest at concentrating but I do manage to get things done. The more time I can’t work for, the more worried I get and the less I can sleep.

I have dealt with death before, nan died last year, the other nan the year before and other family friends and neighbours before that.

I Need to get back to my work but I just can’t do it. Please has anyone got advice on grieving with a busy schedule? I can’t let my masters stop for this. I am doing biology subject and the animals will not wait for me to sort myself out. If I take too long my whole project will fail.