I have just started my last year at uni and believe me I have had THE toughest week. Over the past month or so I have been getting really paranoid about what others think but you have to remember, you can't please everyone and you are at uni for yourself and nobody else. I have walked out of so many lectures crying, just pick yourself up and start again. No one will judge you and if they do they aren't worth your time!
In the way of presentations these freak me out to but I would advise you to get in contact with your student support worker or something similar. At my university I have a learning contract put in place where if I feel like I cant cope doing a presentation, the teachers take that into consideration and mark me based on the work I have done rather than the presentation, this is a good option if the prospect of a presentation scares you.
Remember not to worry at all about what others think, they have no idea what you are going through and if they do they would completely understand
Feel free to PM me if you are struggling with anything at uni..