I've always been mildly dyslexic, but after a head injury when I was 19, it got a lot worse.
In the short term, I could barely read or write at all for a couple of weeks. Letters moved around on the page, I couldn't spell, couldn't remember phone numbers or simple numerical sequences (great fun when working in retail). I also stumbled and stuttered when I tried to speak.
After a few weeks, I was functional again, but 10 years later, I still have a lot of problems with dyslexia, especially with screwed up sequences of letters and/or numbers, and when speaking. I still occasionally stumble over words (can't get the word from my brain to my mouth, say the wrong word altogether, can't enunciate...this is a source of great frustration because I'd had perfect diction prior to that). My reading comprehension and short term memory recall also took a hit, but have improved sloooooowly over time.
ETA: My injury was a concussion caused by two impacts to the back of my head after what amounted to a seizure...I fell back and hit a window, then a marble floor. A CT scan wasn't performed until about 3 weeks later in spite of symptoms that indicated a possible impending hemorrhage (some strongly-worded letters were sent shortly thereafter), so I don't know if there was any swelling or anything like that. The doctor told me I had two concussions and left it at that.