Lyme disease. It doesn't cause fatal problems with most people who catch it but the medical system is terrible at diagnosing and treating it. I remember a study a few years back that I think found either 80% or more people who they were able to diagose and treat(usually only for a month if I remember the protocol correctly) had still had problems even after treatment. The problem is there are so many symptoms that it often gets misdiagnosed and the tests for it suck. They pretty much did every test they could think of and ironically all it took was a simple blood test only done by some lab in CA. I had all kinds of problems like stomach pain, nausea, swollen ankles and knees(to the point I needed crutches), fatigue, difficulty thinking, sensitivity to light, weak immune system, neurological and motor issues, and a few others I'm probably missing. The worst problems got solved between years 2-4 but I still have some problems and it's taking a long time to recover. I never lost the fatigue and in between all this I lost my friends because I was too sick to do much or they just moved away on. When I started high school it was with a new class so I got somewhat of a fresh start but I was too tired to do anything except schoolwork and play video games and after everything that had happened I didn't feel like I belonged and didn't really want new friendships. I pretty much just did my work, got along with my neighbors, and made jokes all through high school(which made me liked with students but I was always studious and got along with teachers). It could have been worse so I don't really care. College has been more of the same. I'll probably try making friends when my health and energy are better and my life is in better order. My long term patience is pretty remarkable now that I look at it since I've been sick for 8 years now