I would ask. I didn't and I regret it. It's not just about the test-taking accommodations etc., its sort of a mental cushion in case things do go south. I didn't do this for myself so when I was having a really hard time I felt like I just had to white knuckle it. No one knew I was struggling with BP, so I had no support. Instead my professors assumed I was unfocused or lazy or unmotivated etc., which caused even more stress. Set yourself up for success!! You might not even need any special accommodations, but they will be there for you just in case. It's absolutely nothing to be ashamed of