Any advice?

Any advice? I'm so screwed I have a 20-minute presentation for my science class the next week or so and my speech block has become exponentially worse. I can't even read off something anymore or talk to anyone without having a million speech blocks and stuttering now. I'm so scared that I'm just going to have speech blocks and start panicking for my presentation and then embarrass myself in front of my peers. Worst of all, my teacher will ask a bunch of questions to test us so I can't even prepare myself beforehand for those either. Any tips? I'm so scared oh god